Index: head/share/man/man4/ddb.4 =================================================================== --- head/share/man/man4/ddb.4 (revision 335436) +++ head/share/man/man4/ddb.4 (revision 335437) @@ -1,1579 +1,1584 @@ .\" .\" Mach Operating System .\" Copyright (c) 1991,1990 Carnegie Mellon University .\" Copyright (c) 2007 Robert N. M. Watson .\" All Rights Reserved. .\" .\" Permission to use, copy, modify and distribute this software and its .\" documentation is hereby granted, provided that both the copyright .\" notice and this permission notice appear in all copies of the .\" software, derivative works or modified versions, and any portions .\" thereof, and that both notices appear in supporting documentation. .\" .\" CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" .\" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR .\" ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. .\" .\" Carnegie Mellon requests users of this software to return to .\" .\" Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU .\" School of Computer Science .\" Carnegie Mellon University .\" Pittsburgh PA 15213-3890 .\" .\" any improvements or extensions that they make and grant Carnegie Mellon .\" the rights to redistribute these changes. .\" .\" changed a \# to #, since groff choked on it. .\" .\" HISTORY .\" ddb.4,v .\" Revision 1.1 1993/07/15 18:41:02 brezak .\" Man page for DDB .\" .\" Revision 2.6 92/04/08 08:52:57 rpd .\" Changes from OSF. .\" [92/01/17 14:19:22 jsb] .\" Changes for OSF debugger modifications. .\" [91/12/12 tak] .\" .\" Revision 2.5 91/06/25 13:50:22 rpd .\" Added some watchpoint explanation. .\" [91/06/25 rpd] .\" .\" Revision 2.4 91/06/17 15:47:31 jsb .\" Added documentation for continue/c, match, search, and watchpoints. .\" I've not actually explained what a watchpoint is; maybe Rich can .\" do that (hint, hint). .\" [91/06/17 10:58:08 jsb] .\" .\" Revision 2.3 91/05/14 17:04:23 mrt .\" Correcting copyright .\" .\" Revision 2.2 91/02/14 14:10:06 mrt .\" Changed to new Mach copyright .\" [91/02/12 18:10:12 mrt] .\" .\" Revision 2.2 90/08/30 14:23:15 dbg .\" Created. .\" [90/08/30 dbg] .\" .\" $FreeBSD$ .\" -.Dd August 24, 2017 +.Dd June 20, 2018 .Dt DDB 4 .Os .Sh NAME .Nm ddb .Nd interactive kernel debugger .Sh SYNOPSIS In order to enable kernel debugging facilities include: .Bd -ragged -offset indent .Cd options KDB .Cd options DDB .Ed .Pp To prevent activation of the debugger on kernel .Xr panic 9 : .Bd -ragged -offset indent .Cd options KDB_UNATTENDED .Ed .Pp In order to print a stack trace of the current thread on the console for a panic: .Bd -ragged -offset indent .Cd options KDB_TRACE .Ed .Pp To print the numerical value of symbols in addition to the symbolic representation, define: .Bd -ragged -offset indent .Cd options DDB_NUMSYM .Ed .Pp To enable the .Xr gdb 1 backend, so that remote debugging with .Xr kgdb 1 is possible, include: .Bd -ragged -offset indent .Cd options GDB .Ed .Sh DESCRIPTION The .Nm kernel debugger is an interactive debugger with a syntax inspired by .Xr gdb 1 . If linked into the running kernel, it can be invoked locally with the .Ql debug .Xr keymap 5 action. The debugger is also invoked on kernel .Xr panic 9 if the .Va debug.debugger_on_panic .Xr sysctl 8 MIB variable is set non-zero, which is the default unless the .Dv KDB_UNATTENDED option is specified. .Pp The current location is called .Va dot . The .Va dot is displayed with a hexadecimal format at a prompt. The commands .Ic examine and .Ic write update .Va dot to the address of the last line examined or the last location modified, and set .Va next to the address of the next location to be examined or changed. Other commands do not change .Va dot , and set .Va next to be the same as .Va dot . .Pp The general command syntax is: .Ar command Ns Op Li / Ns Ar modifier .Oo Ar addr Oc Ns Op , Ns Ar count .Pp A blank line repeats the previous command from the address .Va next with count 1 and no modifiers. Specifying .Ar addr sets .Va dot to the address. Omitting .Ar addr uses .Va dot . A missing .Ar count is taken to be 1 for printing commands or infinity for stack traces. A .Ar count of -1 is equivalent to a missing .Ar count . Options that are supplied but not supported by the given .Ar command are usually ignored. .Pp The .Nm debugger has a pager feature (like the .Xr more 1 command) for the output. If an output line exceeds the number set in the .Va lines variable, it displays .Dq Li --More-- and waits for a response. The valid responses for it are: .Pp .Bl -tag -compact -width ".Li SPC" .It Li SPC one more page .It Li RET one more line .It Li q abort the current command, and return to the command input mode .El .Pp Finally, .Nm provides a small (currently 10 items) command history, and offers simple .Nm emacs Ns -style command line editing capabilities. In addition to the .Nm emacs control keys, the usual .Tn ANSI arrow keys may be used to browse through the history buffer, and move the cursor within the current line. .Sh COMMANDS .Bl -tag -width indent -compact .It Xo .Ic examine Ns Op Li / Ns Cm AISabcdghilmorsuxz ... .Oo Ar addr Oc Ns Op , Ns Ar count .Xc .It Xo .Ic x Ns Op Li / Ns Cm AISabcdghilmorsuxz ... .Oo Ar addr Oc Ns Op , Ns Ar count .Xc Display the addressed locations according to the formats in the modifier. Multiple modifier formats display multiple locations. If no format is specified, the last format specified for this command is used. .Pp The format characters are: .Bl -tag -compact -width indent .It Cm b look at by bytes (8 bits) .It Cm h look at by half words (16 bits) .It Cm l look at by long words (32 bits) .It Cm g look at by quad words (64 bits) .It Cm a print the location being displayed .It Cm A print the location with a line number if possible .It Cm x display in unsigned hex .It Cm z display in signed hex .It Cm o display in unsigned octal .It Cm d display in signed decimal .It Cm u display in unsigned decimal .It Cm r display in current radix, signed .It Cm c display low 8 bits as a character. Non-printing characters are displayed as an octal escape code (e.g., .Ql \e000 ) . .It Cm s display the null-terminated string at the location. Non-printing characters are displayed as octal escapes. .It Cm m display in unsigned hex with character dump at the end of each line. The location is also displayed in hex at the beginning of each line. .It Cm i display as an instruction .It Cm I display as an instruction with possible alternate formats depending on the machine. On i386, this selects the alternate format for the instruction decoding (16 bits in a 32-bit code segment and vice versa). .It Cm S display a symbol name for the pointer stored at the address .El .Pp .It Ic xf Examine forward: execute an .Ic examine command with the last specified parameters to it except that the next address displayed by it is used as the start address. .Pp .It Ic xb Examine backward: execute an .Ic examine command with the last specified parameters to it except that the last start address subtracted by the size displayed by it is used as the start address. .Pp .It Ic print Ns Op Li / Ns Cm acdoruxz .It Ic p Ns Op Li / Ns Cm acdoruxz Print .Ar addr Ns s according to the modifier character (as described above for .Cm examine ) . Valid formats are: .Cm a , x , z , o , d , u , r , and .Cm c . If no modifier is specified, the last one specified to it is used. The argument .Ar addr can be a string, in which case it is printed as it is. For example: .Bd -literal -offset indent print/x "eax = " $eax "\enecx = " $ecx "\en" .Ed .Pp will print like: .Bd -literal -offset indent eax = xxxxxx ecx = yyyyyy .Ed .Pp .It Xo .Ic write Ns Op Li / Ns Cm bhl .Ar addr expr1 Op Ar expr2 ... .Xc .It Xo .Ic w Ns Op Li / Ns Cm bhl .Ar addr expr1 Op Ar expr2 ... .Xc Write the expressions specified after .Ar addr on the command line at succeeding locations starting with .Ar addr . The write unit size can be specified in the modifier with a letter .Cm b (byte), .Cm h (half word) or .Cm l (long word) respectively. If omitted, long word is assumed. .Pp .Sy Warning : since there is no delimiter between expressions, strange things may happen. It is best to enclose each expression in parentheses. .Pp .It Ic set Li $ Ns Ar variable Oo Li = Oc Ar expr Set the named variable or register with the value of .Ar expr . Valid variable names are described below. .Pp .It Ic break Ns Oo Li / Ns Cm u Oc Oo Ar addr Oc Ns Op , Ns Ar count .It Ic b Ns Oo Li / Ns Cm u Oc Oo Ar addr Oc Ns Op , Ns Ar count Set a break point at .Ar addr . If .Ar count is supplied, the .Ic continue command will not stop at this break point on the first .Ar count \- 1 times that it is hit. If the break point is set, a break point number is printed with .Ql # . This number can be used in deleting the break point or adding conditions to it. .Pp If the .Cm u modifier is specified, this command sets a break point in user address space. Without the .Cm u option, the address is considered to be in the kernel space, and a wrong space address is rejected with an error message. This modifier can be used only if it is supported by machine dependent routines. .Pp .Sy Warning : If a user text is shadowed by a normal user space debugger, user space break points may not work correctly. Setting a break point at the low-level code paths may also cause strange behavior. .Pp .It Ic delete Op Ar addr .It Ic d Op Ar addr .It Ic delete Li # Ns Ar number .It Ic d Li # Ns Ar number Delete the specified break point. The break point can be specified by a break point number with .Ql # , or by using the same .Ar addr specified in the original .Ic break command, or by omitting .Ar addr to get the default address of .Va dot . .Pp .It Ic watch Oo Ar addr Oc Ns Op , Ns Ar size Set a watchpoint for a region. Execution stops when an attempt to modify the region occurs. The .Ar size argument defaults to 4. If you specify a wrong space address, the request is rejected with an error message. .Pp .Sy Warning : Attempts to watch wired kernel memory may cause unrecoverable error in some systems such as i386. Watchpoints on user addresses work best. .Pp .It Ic hwatch Oo Ar addr Oc Ns Op , Ns Ar size Set a hardware watchpoint for a region if supported by the architecture. Execution stops when an attempt to modify the region occurs. The .Ar size argument defaults to 4. .Pp .Sy Warning : The hardware debug facilities do not have a concept of separate address spaces like the watch command does. Use .Ic hwatch for setting watchpoints on kernel address locations only, and avoid its use on user mode address spaces. .Pp .It Ic dhwatch Oo Ar addr Oc Ns Op , Ns Ar size Delete specified hardware watchpoint. .Pp .It Ic step Ns Oo Li / Ns Cm p Oc Ns Op , Ns Ar count .It Ic s Ns Oo Li / Ns Cm p Oc Ns Op , Ns Ar count Single step .Ar count times. If the .Cm p modifier is specified, print each instruction at each step. Otherwise, only print the last instruction. .Pp .Sy Warning : depending on machine type, it may not be possible to single-step through some low-level code paths or user space code. On machines with software-emulated single-stepping (e.g., pmax), stepping through code executed by interrupt handlers will probably do the wrong thing. .Pp .It Ic continue Ns Op Li / Ns Cm c .It Ic c Ns Op Li / Ns Cm c Continue execution until a breakpoint or watchpoint. If the .Cm c modifier is specified, count instructions while executing. Some machines (e.g., pmax) also count loads and stores. .Pp .Sy Warning : when counting, the debugger is really silently single-stepping. This means that single-stepping on low-level code may cause strange behavior. .Pp .It Ic until Ns Op Li / Ns Cm p Stop at the next call or return instruction. If the .Cm p modifier is specified, print the call nesting depth and the cumulative instruction count at each call or return. Otherwise, only print when the matching return is hit. .Pp .It Ic next Ns Op Li / Ns Cm p .It Ic match Ns Op Li / Ns Cm p Stop at the matching return instruction. If the .Cm p modifier is specified, print the call nesting depth and the cumulative instruction count at each call or return. Otherwise, only print when the matching return is hit. .Pp .It Xo .Ic trace Ns Op Li / Ns Cm u .Op Ar pid | tid Ns .Op , Ns Ar count .Xc .It Xo .Ic t Ns Op Li / Ns Cm u .Op Ar pid | tid Ns .Op , Ns Ar count .Xc .It Xo .Ic where Ns Op Li / Ns Cm u .Op Ar pid | tid Ns .Op , Ns Ar count .Xc .It Xo .Ic bt Ns Op Li / Ns Cm u .Op Ar pid | tid Ns .Op , Ns Ar count .Xc Stack trace. The .Cm u option traces user space; if omitted, .Ic trace only traces kernel space. The optional argument .Ar count is the number of frames to be traced. If .Ar count is omitted, all frames are printed. .Pp .Sy Warning : User space stack trace is valid only if the machine dependent code supports it. .Pp .It Xo .Ic search Ns Op Li / Ns Cm bhl .Ar addr .Ar value .Op Ar mask Ns .Op , Ns Ar count .Xc Search memory for .Ar value . The optional .Ar count argument limits the search. .\" .Pp .It Xo .Ic findstack .Ar addr .Xc Prints the thread address for a thread kernel-mode stack of which contains the specified address. If the thread is not found, search the thread stack cache and prints the cached stack address. Otherwise, prints nothing. .Pp .It Ic show Cm all procs Ns Op Li / Ns Cm m .It Ic ps Ns Op Li / Ns Cm m Display all process information. The process information may not be shown if it is not supported in the machine, or the bottom of the stack of the target process is not in the main memory at that time. The .Cm m modifier will alter the display to show VM map addresses for the process and not show other information. .\" .Pp .It Ic show Cm all trace .It Ic alltrace Show a stack trace for every thread in the system. .Pp .It Ic show Cm all ttys Show all TTY's within the system. Output is similar to .Xr pstat 8 , but also includes the address of the TTY structure. .\" .Pp .It Ic show Cm all vnets Show the same output as "show vnet" does, but lists all virtualized network stacks within the system. .\" .Pp .It Ic show Cm allchains Show the same information like "show lockchain" does, but for every thread in the system. .\" .Pp .It Ic show Cm alllocks Show all locks that are currently held. This command is only available if .Xr witness 4 is included in the kernel. .\" .Pp .It Ic show Cm allpcpu The same as "show pcpu", but for every CPU present in the system. .\" .Pp .It Ic show Cm allrman Show information related with resource management, including interrupt request lines, DMA request lines, I/O ports, I/O memory addresses, and Resource IDs. .\" .Pp .It Ic show Cm apic Dump data about APIC IDT vector mappings. .\" .Pp .It Ic show Cm breaks Show breakpoints set with the "break" command. .\" .Pp .It Ic show Cm bio Ar addr Show information about the bio structure .Vt struct bio present at .Ar addr . See the .Pa sys/bio.h header file and .Xr g_bio 9 for more details on the exact meaning of the structure fields. .\" .Pp .It Ic show Cm buffer Ar addr Show information about the buf structure .Vt struct buf present at .Ar addr . See the .Pa sys/buf.h header file for more details on the exact meaning of the structure fields. .\" .Pp .It Ic show Cm callout Ar addr Show information about the callout structure .Vt struct callout present at .Ar addr . .\" .Pp .It Ic show Cm cbstat Show brief information about the TTY subsystem. .\" .Pp .It Ic show Cm cdev Without argument, show the list of all created cdev's, consisting of devfs node name and struct cdev address. When address of cdev is supplied, show some internal devfs state of the cdev. .\" .Pp .It Ic show Cm conifhk Lists hooks currently waiting for completion in run_interrupt_driven_config_hooks(). .\" .Pp .It Ic show Cm cpusets Print numbered root and assigned CPU affinity sets. See .Xr cpuset 2 for more details. .\" .Pp .It Ic show Cm cyrixreg Show registers specific to the Cyrix processor. .\" .Pp .It Ic show Cm devmap Prints the contents of the static device mapping table. Currently only available on the ARM architecture. .\" .Pp .It Ic show Cm domain Ar addr Print protocol domain structure .Vt struct domain at address .Ar addr . See the .Pa sys/domain.h header file for more details on the exact meaning of the structure fields. .\" .Pp .It Ic show Cm ffs Op Ar addr Show brief information about ffs mount at the address .Ar addr , if argument is given. Otherwise, provides the summary about each ffs mount. .\" .Pp .It Ic show Cm file Ar addr Show information about the file structure .Vt struct file present at address .Ar addr . .\" .Pp .It Ic show Cm files Show information about every file structure in the system. .\" .Pp .It Ic show Cm freepages Show the number of physical pages in each of the free lists. .\" .Pp .It Ic show Cm geom Op Ar addr If the .Ar addr argument is not given, displays the entire GEOM topology. If .Ar addr is given, displays details about the given GEOM object (class, geom, provider or consumer). .\" .Pp .It Ic show Cm idt Show IDT layout. The first column specifies the IDT vector. The second one is the name of the interrupt/trap handler. Those functions are machine dependent. .\" .Pp .It Ic show Cm igi_list Ar addr Show information about the IGMP structure .Vt struct igmp_ifsoftc present at .Ar addr . .\" .Pp .It Ic show Cm inodedeps Op Ar addr Show brief information about each inodedep structure. If .Ar addr is given, only inodedeps belonging to the fs located at the supplied address are shown. .\" .Pp .It Ic show Cm inpcb Ar addr Show information on IP Control Block .Vt struct in_pcb present at .Ar addr . .\" .Pp .It Ic show Cm intr Dump information about interrupt handlers. .\" .Pp .It Ic show Cm intrcnt Dump the interrupt statistics. .\" .Pp .It Ic show Cm irqs Show interrupt lines and their respective kernel threads. .\" .Pp .It Ic show Cm jails Show the list of .Xr jail 8 instances. In addition to what .Xr jls 8 shows, also list kernel internal details. .\" .Pp .It Ic show Cm lapic Show information from the local APIC registers for this CPU. .\" .Pp .It Ic show Cm lock Ar addr Show lock structure. The output format is as follows: .Bl -tag -width "flags" .It Ic class: Class of the lock. Possible types include .Xr mutex 9 , .Xr rmlock 9 , .Xr rwlock 9 , .Xr sx 9 . .It Ic name: Name of the lock. .It Ic flags: Flags passed to the lock initialization function. .Em flags values are lock class specific. .It Ic state: Current state of a lock. .Em state values are lock class specific. .It Ic owner: Lock owner. .El .\" .Pp .It Ic show Cm lockchain Ar addr Show all threads a particular thread at address .Ar addr is waiting on based on non-spin locks. .\" .Pp .It Ic show Cm lockedbufs Show the same information as "show buf", but for every locked .Vt struct buf object. .\" .Pp .It Ic show Cm lockedvnods List all locked vnodes in the system. .\" .Pp .It Ic show Cm locks Prints all locks that are currently acquired. This command is only available if .Xr witness 4 is included in the kernel. .\" .Pp .It Ic show Cm locktree .\" .Pp .It Ic show Cm malloc Prints .Xr malloc 9 memory allocator statistics. The output format is as follows: .Pp .Bl -tag -compact -offset indent -width "Requests" .It Ic Type Specifies a type of memory. It is the same as a description string used while defining the given memory type with .Xr MALLOC_DECLARE 9 . .It Ic InUse Number of memory allocations of the given type, for which .Xr free 9 has not been called yet. .It Ic MemUse Total memory consumed by the given allocation type. .It Ic Requests Number of memory allocation requests for the given memory type. .El .Pp The same information can be gathered in userspace with .Dq Nm vmstat Fl m . .\" .Pp .It Ic show Cm map Ns Oo Li / Ns Cm f Oc Ar addr Prints the VM map at .Ar addr . If the .Cm f modifier is specified the complete map is printed. .\" .Pp .It Ic show Cm msgbuf Print the system's message buffer. It is the same output as in the .Dq Nm dmesg case. It is useful if you got a kernel panic, attached a serial cable to the machine and want to get the boot messages from before the system hang. .\" .It Ic show Cm mount Displays short info about all currently mounted file systems. .Pp .It Ic show Cm mount Ar addr Displays details about the given mount point. .\" .Pp .It Ic show Cm object Ns Oo Li / Ns Cm f Oc Ar addr Prints the VM object at .Ar addr . If the .Cm f option is specified the complete object is printed. .\" .Pp .It Ic show Cm panic Print the panic message if set. .\" .Pp .It Ic show Cm page Show statistics on VM pages. .\" .Pp .It Ic show Cm pageq Show statistics on VM page queues. .\" .Pp .It Ic show Cm pciregs Print PCI bus registers. The same information can be gathered in userspace by running .Dq Nm pciconf Fl lv . .\" .Pp .It Ic show Cm pcpu Print current processor state. The output format is as follows: .Pp .Bl -tag -compact -offset indent -width "spin locks held:" .It Ic cpuid Processor identifier. .It Ic curthread Thread pointer, process identifier and the name of the process. .It Ic curpcb Control block pointer. .It Ic fpcurthread FPU thread pointer. .It Ic idlethread Idle thread pointer. .It Ic APIC ID CPU identifier coming from APIC. .It Ic currentldt LDT pointer. .It Ic spin locks held Names of spin locks held. .El .\" .Pp .It Ic show Cm pgrpdump Dump process groups present within the system. .\" .Pp .It Ic show Cm proc Op Ar addr If no .Op Ar addr is specified, print information about the current process. Otherwise, show information about the process at address .Ar addr . .\" .Pp .It Ic show Cm procvm Show process virtual memory layout. .\" .Pp .It Ic show Cm protosw Ar addr Print protocol switch structure .Vt struct protosw at address .Ar addr . .\" .Pp .It Ic show Cm registers Ns Op Li / Ns Cm u Display the register set. If the .Cm u modifier is specified, it displays user registers instead of kernel registers or the currently saved one. .Pp .Sy Warning : The support of the .Cm u modifier depends on the machine. If not supported, incorrect information will be displayed. .\" .Pp .It Ic show Cm rman Ar addr Show resource manager object .Vt struct rman at address .Ar addr . Addresses of particular pointers can be gathered with "show allrman" command. .\" .Pp .It Ic show Cm rtc Show real time clock value. Useful for long debugging sessions. .\" .Pp .It Ic show Cm sleepchain Deprecated. Now an alias for .Ic show Cm lockchain . .\" .Pp .It Ic show Cm sleepq .It Ic show Cm sleepqueue Both commands provide the same functionality. They show sleepqueue .Vt struct sleepqueue structure. Sleepqueues are used within the .Fx kernel to implement sleepable synchronization primitives (thread holding a lock might sleep or be context switched), which at the time of writing are: .Xr condvar 9 , .Xr sx 9 and standard .Xr msleep 9 interface. .\" .Pp .It Ic show Cm sockbuf Ar addr .It Ic show Cm socket Ar addr Those commands print .Vt struct sockbuf and .Vt struct socket objects placed at .Ar addr . Output consists of all values present in structures mentioned. For exact interpretation and more details, visit .Pa sys/socket.h header file. .\" .Pp .It Ic show Cm sysregs Show system registers (e.g., .Li cr0-4 on i386.) Not present on some platforms. .\" .Pp .It Ic show Cm tcpcb Ar addr Print TCP control block .Vt struct tcpcb lying at address .Ar addr . For exact interpretation of output, visit .Pa netinet/tcp.h header file. .\" .Pp .It Ic show Cm thread Op Ar addr If no .Ar addr is specified, show detailed information about current thread. Otherwise, information about thread at .Ar addr is printed. .\" .Pp .It Ic show Cm threads Show all threads within the system. Output format is as follows: .Pp .Bl -tag -compact -offset indent -width "Second column" .It Ic First column Thread identifier (TID) .It Ic Second column Thread structure address .It Ic Third column Backtrace. .El .\" .Pp .It Ic show Cm tty Ar addr Display the contents of a TTY structure in a readable form. .\" .Pp .It Ic show Cm turnstile Ar addr Show turnstile .Vt struct turnstile structure at address .Ar addr . Turnstiles are structures used within the .Fx kernel to implement synchronization primitives which, while holding a specific type of lock, cannot sleep or context switch to another thread. Currently, those are: .Xr mutex 9 , .Xr rwlock 9 , .Xr rmlock 9 . .\" .Pp .It Ic show Cm uma Show UMA allocator statistics. Output consists five columns: .Pp .Bl -tag -compact -offset indent -width "Requests" .It Cm "Zone" Name of the UMA zone. The same string that was passed to .Xr uma_zcreate 9 as a first argument. .It Cm "Size" Size of a given memory object (slab). .It Cm "Used" Number of slabs being currently used. .It Cm "Free" Number of free slabs within the UMA zone. .It Cm "Requests" Number of allocations requests to the given zone. .El .Pp The very same information might be gathered in the userspace with the help of .Dq Nm vmstat Fl z . .\" .Pp .It Ic show Cm unpcb Ar addr Shows UNIX domain socket private control block .Vt struct unpcb present at the address .Ar addr . .\" .Pp .It Ic show Cm vmochk Prints, whether the internal VM objects are in a map somewhere and none have zero ref counts. .\" .Pp .It Ic show Cm vmopag This is supposed to show physical addresses consumed by a VM object. Currently, it is not possible to use this command when .Xr witness 4 is compiled in the kernel. .\" .Pp .It Ic show Cm vnet Ar addr Prints virtualized network stack .Vt struct vnet structure present at the address .Ar addr . .\" .Pp .It Ic show Cm vnode Op Ar addr Prints vnode .Vt struct vnode structure lying at .Op Ar addr . For the exact interpretation of the output, look at the .Pa sys/vnode.h header file. .\" .Pp .It Ic show Cm vnodebufs Ar addr Shows clean/dirty buffer lists of the vnode located at +.Ar addr . +.\" +.Pp +.It Ic show Cm vpath Ar addr +Walk the namecache to lookup the pathname of the vnode located at .Ar addr . .\" .Pp .It Ic show Cm watches Displays all watchpoints. Shows watchpoints set with "watch" command. .\" .Pp .It Ic show Cm witness Shows information about lock acquisition coming from the .Xr witness 4 subsystem. .\" .Pp .It Ic gdb Toggles between remote GDB and DDB mode. In remote GDB mode, another machine is required that runs .Xr gdb 1 using the remote debug feature, with a connection to the serial console port on the target machine. Currently only available on the i386 architecture. .Pp .It Ic halt Halt the system. .Pp .It Ic kill Ar sig pid Send signal .Ar sig to process .Ar pid . The signal is acted on upon returning from the debugger. This command can be used to kill a process causing resource contention in the case of a hung system. See .Xr signal 3 for a list of signals. Note that the arguments are reversed relative to .Xr kill 2 . .Pp .It Ic reboot Op Ar seconds .It Ic reset Op Ar seconds Hard reset the system. If the optional argument .Ar seconds is given, the debugger will wait for this long, at most a week, before rebooting. .Pp .It Ic help Print a short summary of the available commands and command abbreviations. .Pp .It Ic capture on .It Ic capture off .It Ic capture reset .It Ic capture status .Nm supports a basic output capture facility, which can be used to retrieve the results of debugging commands from userspace using .Xr sysctl 3 . .Ic capture on enables output capture; .Ic capture off disables capture. .Ic capture reset will clear the capture buffer and disable capture. .Ic capture status will report current buffer use, buffer size, and disposition of output capture. .Pp Userspace processes may inspect and manage .Nm capture state using .Xr sysctl 8 : .Pp .Dv debug.ddb.capture.bufsize may be used to query or set the current capture buffer size. .Pp .Dv debug.ddb.capture.maxbufsize may be used to query the compile-time limit on the capture buffer size. .Pp .Dv debug.ddb.capture.bytes may be used to query the number of bytes of output currently in the capture buffer. .Pp .Dv debug.ddb.capture.data returns the contents of the buffer as a string to an appropriately privileged process. .Pp This facility is particularly useful in concert with the scripting and .Xr textdump 4 facilities, allowing scripted debugging output to be captured and committed to disk as part of a textdump for later analysis. The contents of the capture buffer may also be inspected in a kernel core dump using .Xr kgdb 1 . .Pp .It Ic run .It Ic script .It Ic scripts .It Ic unscript Run, define, list, and delete scripts. See the .Sx SCRIPTING section for more information on the scripting facility. .Pp .It Ic textdump dump .It Ic textdump set .It Ic textdump status .It Ic textdump unset Use the .Ic textdump dump command to immediately perform a textdump. More information may be found in .Xr textdump 4 . The .Ic textdump set command may be used to force the next kernel core dump to be a textdump rather than a traditional memory dump or minidump. .Ic textdump status reports whether a textdump has been scheduled. .Ic textdump unset cancels a request to perform a textdump as the next kernel core dump. .El .Sh VARIABLES The debugger accesses registers and variables as .Li $ Ns Ar name . Register names are as in the .Dq Ic show Cm registers command. Some variables are suffixed with numbers, and may have some modifier following a colon immediately after the variable name. For example, register variables can have a .Cm u modifier to indicate user register (e.g., .Dq Li $eax:u ) . .Pp Built-in variables currently supported are: .Pp .Bl -tag -width ".Va tabstops" -compact .It Va radix Input and output radix. .It Va maxoff Addresses are printed as .Dq Ar symbol Ns Li + Ns Ar offset unless .Ar offset is greater than .Va maxoff . .It Va maxwidth The width of the displayed line. .It Va lines The number of lines. It is used by the built-in pager. .It Va tabstops Tab stop width. .It Va work Ns Ar xx Work variable; .Ar xx can take values from 0 to 31. .El .Sh EXPRESSIONS Most expression operators in C are supported except .Ql ~ , .Ql ^ , and unary .Ql & . Special rules in .Nm are: .Bl -tag -width ".No Identifiers" .It Identifiers The name of a symbol is translated to the value of the symbol, which is the address of the corresponding object. .Ql \&. and .Ql \&: can be used in the identifier. If supported by an object format dependent routine, .Sm off .Oo Ar filename : Oc Ar func : lineno , .Sm on .Oo Ar filename : Oc Ns Ar variable , and .Oo Ar filename : Oc Ns Ar lineno can be accepted as a symbol. .It Numbers Radix is determined by the first two letters: .Ql 0x : hex, .Ql 0o : octal, .Ql 0t : decimal; otherwise, follow current radix. .It Li \&. .Va dot .It Li + .Va next .It Li .. address of the start of the last line examined. Unlike .Va dot or .Va next , this is only changed by .Ic examine or .Ic write command. .It Li ' last address explicitly specified. .It Li $ Ns Ar variable Translated to the value of the specified variable. It may be followed by a .Ql \&: and modifiers as described above. .It Ar a Ns Li # Ns Ar b A binary operator which rounds up the left hand side to the next multiple of right hand side. .It Li * Ns Ar expr Indirection. It may be followed by a .Ql \&: and modifiers as described above. .El .Sh SCRIPTING .Nm supports a basic scripting facility to allow automating tasks or responses to specific events. Each script consists of a list of DDB commands to be executed sequentially, and is assigned a unique name. Certain script names have special meaning, and will be automatically run on various .Nm events if scripts by those names have been defined. .Pp The .Ic script command may be used to define a script by name. Scripts consist of a series of .Nm commands separated with the .Ql \&; character. For example: .Bd -literal -offset indent script kdb.enter.panic=bt; show pcpu script lockinfo=show alllocks; show lockedvnods .Ed .Pp The .Ic scripts command lists currently defined scripts. .Pp The .Ic run command execute a script by name. For example: .Bd -literal -offset indent run lockinfo .Ed .Pp The .Ic unscript command may be used to delete a script by name. For example: .Bd -literal -offset indent unscript kdb.enter.panic .Ed .Pp These functions may also be performed from userspace using the .Xr ddb 8 command. .Pp Certain scripts are run automatically, if defined, for specific .Nm events. The follow scripts are run when various events occur: .Bl -tag -width kdb.enter.powerfail .It Dv kdb.enter.acpi The kernel debugger was entered as a result of an .Xr acpi 4 event. .It Dv kdb.enter.bootflags The kernel debugger was entered at boot as a result of the debugger boot flag being set. .It Dv kdb.enter.break The kernel debugger was entered as a result of a serial or console break. .It Dv kdb.enter.cam The kernel debugger was entered as a result of a .Xr CAM 4 event. .It Dv kdb.enter.mac The kernel debugger was entered as a result of an assertion failure in the .Xr mac_test 4 module of the TrustedBSD MAC Framework. .It Dv kdb.enter.ndis The kernel debugger was entered as a result of an .Xr ndis 4 breakpoint event. .It Dv kdb.enter.netgraph The kernel debugger was entered as a result of a .Xr netgraph 4 event. .It Dv kdb.enter.panic .Xr panic 9 was called. .It Dv kdb.enter.powerfail The kernel debugger was entered as a result of a powerfail NMI on the sparc64 platform. .It Dv kdb.enter.powerpc The kernel debugger was entered as a result of an unimplemented interrupt type on the powerpc platform. .It Dv kdb.enter.sysctl The kernel debugger was entered as a result of the .Dv debug.kdb.enter sysctl being set. .It Dv kdb.enter.trapsig The kernel debugger was entered as a result of a trapsig event on the sparc64 platform. .It Dv kdb.enter.unionfs The kernel debugger was entered as a result of an assertion failure in the union file system. .It Dv kdb.enter.unknown The kernel debugger was entered, but no reason has been set. .It Dv kdb.enter.vfslock The kernel debugger was entered as a result of a VFS lock violation. .It Dv kdb.enter.watchdog The kernel debugger was entered as a result of a watchdog firing. .It Dv kdb.enter.witness The kernel debugger was entered as a result of a .Xr witness 4 violation. .El .Pp In the event that none of these scripts is found, .Nm will attempt to execute a default script: .Bl -tag -width kdb.enter.powerfail .It Dv kdb.enter.default The kernel debugger was entered, but a script exactly matching the reason for entering was not defined. This can be used as a catch-all to handle cases not specifically of interest; for example, .Dv kdb.enter.witness might be defined to have special handling, and .Dv kdb.enter.default might be defined to simply panic and reboot. .El .Sh HINTS On machines with an ISA expansion bus, a simple NMI generation card can be constructed by connecting a push button between the A01 and B01 (CHCHK# and GND) card fingers. Momentarily shorting these two fingers together may cause the bridge chipset to generate an NMI, which causes the kernel to pass control to .Nm . Some bridge chipsets do not generate a NMI on CHCHK#, so your mileage may vary. The NMI allows one to break into the debugger on a wedged machine to diagnose problems. Other bus' bridge chipsets may be able to generate NMI using bus specific methods. There are many PCI and PCIe add-in cards which can generate NMI for debugging. Modern server systems typically use IPMI to generate signals to enter the debugger. The .Dv devel/ipmitool port can be used to send the .Cd chassis power diag command which delivers an NMI to the processor. Embedded systems often use JTAG for debugging, but rarely use it in combination with .Nm . .Pp For serial consoles, you can enter the debugger by sending a BREAK condition on the serial line if .Cd options BREAK_TO_DEBUGGER is specified in the kernel. Most terminal emulation programs can send a break sequence with a special key sequence or via a menu item. However, in some setups, sending the break can be difficult to arrange or happens spuriously, so if the kernel contains .Cd options ALT_BREAK_TO_DEBUGGER then the sequence of CR TILDE CTRL-B enters the debugger; CR TILDE CTRL-P causes a panic instead of entering the debugger; and CR TILDE CTRL-R causes an immediate reboot. In all the above sequences, CR is a Carriage Return and is usually sent by hitting the Enter or Return key. TILDE is the ASCII tilde character (~). CTRL-x is Control x created by hitting the control key and then x and then releasing both. .Pp The break to enter the debugger behavior may be enabled at run-time by setting the .Xr sysctl 8 .Dv debug.kdb.break_to_debugger to 1. The alternate sequence to enter the debugger behavior may be enabled at run-time by setting the .Xr sysctl 8 .Dv debug.kdb.alt_break_to_debugger to 1. The debugger may be entered by setting the .Xr sysctl 8 .Dv debug.kdb.enter to 1. .Sh FILES Header files mentioned in this manual page can be found below .Pa /usr/include directory. .Pp .Bl -dash -compact .It .Pa sys/buf.h .It .Pa sys/domain.h .It .Pa netinet/in_pcb.h .It .Pa sys/socket.h .It .Pa sys/vnode.h .El .Sh SEE ALSO .Xr gdb 1 , .Xr kgdb 1 , .Xr acpi 4 , .Xr CAM 4 , .Xr mac_test 4 , .Xr ndis 4 , .Xr netgraph 4 , .Xr textdump 4 , .Xr witness 4 , .Xr ddb 8 , .Xr sysctl 8 , .Xr panic 9 .Sh HISTORY The .Nm debugger was developed for Mach, and ported to .Bx 386 0.1 . This manual page translated from .Xr man 7 macros by .An Garrett Wollman . .Pp .An Robert N. M. Watson added support for .Nm output capture, .Xr textdump 4 and scripting in .Fx 7.1 . Index: head/sys/kern/vfs_cache.c =================================================================== --- head/sys/kern/vfs_cache.c (revision 335436) +++ head/sys/kern/vfs_cache.c (revision 335437) @@ -1,2531 +1,2587 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1989, 1993, 1995 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Poul-Henning Kamp of the FreeBSD Project. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 */ #include __FBSDID("$FreeBSD$"); +#include "opt_ddb.h" #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #endif +#ifdef DDB +#include +#endif + #include SDT_PROVIDER_DECLARE(vfs); SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", "char *"); SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", "struct vnode *", "char *"); SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, "struct vnode *", "char *"); SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", "char *"); SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE3(vfs, namecache, zap_negative, done, "struct vnode *", "char *", "int"); SDT_PROBE_DEFINE3(vfs, namecache, shrink_negative, done, "struct vnode *", "char *", "int"); /* * This structure describes the elements in the cache of recent * names looked up by namei. */ struct namecache { LIST_ENTRY(namecache) nc_hash; /* hash chain */ LIST_ENTRY(namecache) nc_src; /* source vnode list */ TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ struct vnode *nc_dvp; /* vnode of parent of name */ union { struct vnode *nu_vp; /* vnode the name refers to */ u_int nu_neghits; /* negative entry hits */ } n_un; u_char nc_flag; /* flag bits */ u_char nc_nlen; /* length of name */ char nc_name[0]; /* segment name + nul */ }; /* * struct namecache_ts repeats struct namecache layout up to the * nc_nlen member. * struct namecache_ts is used in place of struct namecache when time(s) need * to be stored. The nc_dotdottime field is used when a cache entry is mapping * both a non-dotdot directory name plus dotdot for the directory's * parent. */ struct namecache_ts { struct timespec nc_time; /* timespec provided by fs */ struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ int nc_ticks; /* ticks value when entry was added */ struct namecache nc_nc; }; #define nc_vp n_un.nu_vp #define nc_neghits n_un.nu_neghits /* * Flags in namecache.nc_flag */ #define NCF_WHITE 0x01 #define NCF_ISDOTDOT 0x02 #define NCF_TS 0x04 #define NCF_DTS 0x08 #define NCF_DVDROP 0x10 #define NCF_NEGATIVE 0x20 #define NCF_HOTNEGATIVE 0x40 /* * Name caching works as follows: * * Names found by directory scans are retained in a cache * for future reference. It is managed LRU, so frequently * used names will hang around. Cache is indexed by hash value * obtained from (vp, name) where vp refers to the directory * containing name. * * If it is a "negative" entry, (i.e. for a name that is known NOT to * exist) the vnode pointer will be NULL. * * Upon reaching the last segment of a path, if the reference * is for DELETE, or NOCACHE is set (rewrite), and the * name is located in the cache, it will be dropped. * * These locks are used (in the order in which they can be taken): * NAME TYPE ROLE * vnodelock mtx vnode lists and v_cache_dd field protection * bucketlock rwlock for access to given set of hash buckets * neglist mtx negative entry LRU management * * Additionally, ncneg_shrink_lock mtx is used to have at most one thread * shrinking the LRU list. * * It is legal to take multiple vnodelock and bucketlock locks. The locking * order is lower address first. Both are recursive. * * "." lookups are lockless. * * ".." and vnode -> name lookups require vnodelock. * * name -> vnode lookup requires the relevant bucketlock to be held for reading. * * Insertions and removals of entries require involved vnodes and bucketlocks * to be write-locked to prevent other threads from seeing the entry. * * Some lookups result in removal of the found entry (e.g. getting rid of a * negative entry with the intent to create a positive one), which poses a * problem when multiple threads reach the state. Similarly, two different * threads can purge two different vnodes and try to remove the same name. * * If the already held vnode lock is lower than the second required lock, we * can just take the other lock. However, in the opposite case, this could * deadlock. As such, this is resolved by trylocking and if that fails unlocking * the first node, locking everything in order and revalidating the state. */ /* * Structures associated with name caching. */ #define NCHHASH(hash) \ (&nchashtbl[(hash) & nchash]) static __read_mostly LIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */ static u_long __read_mostly nchash; /* size of hash table */ SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, "Size of namecache hash table"); static u_long __read_mostly ncnegfactor = 12; /* ratio of negative entries */ SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, "Ratio of negative namecache entries"); static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */ SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, "Number of negative entries in namecache"); static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */ SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "Number of namecache entries"); static u_long __exclusive_cache_line numcachehv;/* number of cache entries with vnodes held */ SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, "Number of namecache entries with vnodes held"); u_int __read_mostly ncsizefactor = 2; SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, "Size factor for namecache"); static u_int __read_mostly ncpurgeminvnodes; SYSCTL_UINT(_vfs, OID_AUTO, ncpurgeminvnodes, CTLFLAG_RW, &ncpurgeminvnodes, 0, "Number of vnodes below which purgevfs ignores the request"); static u_int __read_mostly ncneghitsrequeue = 8; SYSCTL_UINT(_vfs, OID_AUTO, ncneghitsrequeue, CTLFLAG_RW, &ncneghitsrequeue, 0, "Number of hits to requeue a negative entry in the LRU list"); struct nchstats nchstats; /* cache effectiveness statistics */ static struct mtx ncneg_shrink_lock; static int shrink_list_turn; struct neglist { struct mtx nl_lock; TAILQ_HEAD(, namecache) nl_list; } __aligned(CACHE_LINE_SIZE); static struct neglist __read_mostly *neglists; static struct neglist ncneg_hot; #define numneglists (ncneghash + 1) static u_int __read_mostly ncneghash; static inline struct neglist * NCP2NEGLIST(struct namecache *ncp) { return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]); } #define numbucketlocks (ncbuckethash + 1) static u_int __read_mostly ncbuckethash; static struct rwlock_padalign __read_mostly *bucketlocks; #define HASH2BUCKETLOCK(hash) \ ((struct rwlock *)(&bucketlocks[((hash) & ncbuckethash)])) #define numvnodelocks (ncvnodehash + 1) static u_int __read_mostly ncvnodehash; static struct mtx __read_mostly *vnodelocks; static inline struct mtx * VP2VNODELOCK(struct vnode *vp) { return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]); } /* * UMA zones for the VFS cache. * * The small cache is used for entries with short names, which are the * most common. The large cache is used for entries which are too big to * fit in the small cache. */ static uma_zone_t __read_mostly cache_zone_small; static uma_zone_t __read_mostly cache_zone_small_ts; static uma_zone_t __read_mostly cache_zone_large; static uma_zone_t __read_mostly cache_zone_large_ts; #define CACHE_PATH_CUTOFF 35 static struct namecache * cache_alloc(int len, int ts) { struct namecache_ts *ncp_ts; struct namecache *ncp; if (__predict_false(ts)) { if (len <= CACHE_PATH_CUTOFF) ncp_ts = uma_zalloc(cache_zone_small_ts, M_WAITOK); else ncp_ts = uma_zalloc(cache_zone_large_ts, M_WAITOK); ncp = &ncp_ts->nc_nc; } else { if (len <= CACHE_PATH_CUTOFF) ncp = uma_zalloc(cache_zone_small, M_WAITOK); else ncp = uma_zalloc(cache_zone_large, M_WAITOK); } return (ncp); } static void cache_free(struct namecache *ncp) { struct namecache_ts *ncp_ts; if (ncp == NULL) return; if ((ncp->nc_flag & NCF_DVDROP) != 0) vdrop(ncp->nc_dvp); if (__predict_false(ncp->nc_flag & NCF_TS)) { ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) uma_zfree(cache_zone_small_ts, ncp_ts); else uma_zfree(cache_zone_large_ts, ncp_ts); } else { if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) uma_zfree(cache_zone_small, ncp); else uma_zfree(cache_zone_large, ncp); } } static void cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) { struct namecache_ts *ncp_ts; KASSERT((ncp->nc_flag & NCF_TS) != 0 || (tsp == NULL && ticksp == NULL), ("No NCF_TS")); if (tsp == NULL && ticksp == NULL) return; ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); if (tsp != NULL) *tsp = ncp_ts->nc_time; if (ticksp != NULL) *ticksp = ncp_ts->nc_ticks; } static int __read_mostly doingcache = 1; /* 1 => enable the cache */ SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, "VFS namecache enabled"); /* Export size information to userland */ SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, sizeof(struct namecache), "sizeof(struct namecache)"); /* * The new name cache statistics */ static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); #define STATNODE_ULONG(name, descr) \ SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr); #define STATNODE_COUNTER(name, descr) \ static counter_u64_t __read_mostly name; \ SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr); STATNODE_ULONG(numneg, "Number of negative cache entries"); STATNODE_ULONG(numcache, "Number of cache entries"); STATNODE_COUNTER(numcalls, "Number of cache lookups"); STATNODE_COUNTER(dothits, "Number of '.' hits"); STATNODE_COUNTER(dotdothits, "Number of '..' hits"); STATNODE_COUNTER(numchecks, "Number of checks in lookup"); STATNODE_COUNTER(nummiss, "Number of cache misses"); STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache"); STATNODE_COUNTER(numposzaps, "Number of cache hits (positive) we do not want to cache"); STATNODE_COUNTER(numposhits, "Number of cache hits (positive)"); STATNODE_COUNTER(numnegzaps, "Number of cache hits (negative) we do not want to cache"); STATNODE_COUNTER(numneghits, "Number of cache hits (negative)"); /* These count for kern___getcwd(), too. */ STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls"); STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); STATNODE_COUNTER(numfullpathfail2, "Number of fullpath search errors (VOP_VPTOCNP failures)"); STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls"); static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail, "Number of times zap_and_exit failed to lock"); static long cache_lock_vnodes_cel_3_failures; STATNODE_ULONG(cache_lock_vnodes_cel_3_failures, "Number of times 3-way vnode locking failed"); static void cache_zap_locked(struct namecache *ncp, bool neg_locked); static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, u_int buflen); static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); static int cache_yield; SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0, "Number of times cache called yield"); static void cache_maybe_yield(void) { if (should_yield()) { cache_yield++; kern_yield(PRI_USER); } } static inline void cache_assert_vlp_locked(struct mtx *vlp) { if (vlp != NULL) mtx_assert(vlp, MA_OWNED); } static inline void cache_assert_vnode_locked(struct vnode *vp) { struct mtx *vlp; vlp = VP2VNODELOCK(vp); cache_assert_vlp_locked(vlp); } static uint32_t cache_get_hash(char *name, u_char len, struct vnode *dvp) { uint32_t hash; hash = fnv_32_buf(name, len, FNV1_32_INIT); hash = fnv_32_buf(&dvp, sizeof(dvp), hash); return (hash); } static inline struct rwlock * NCP2BUCKETLOCK(struct namecache *ncp) { uint32_t hash; hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); return (HASH2BUCKETLOCK(hash)); } #ifdef INVARIANTS static void cache_assert_bucket_locked(struct namecache *ncp, int mode) { struct rwlock *blp; blp = NCP2BUCKETLOCK(ncp); rw_assert(blp, mode); } #else #define cache_assert_bucket_locked(x, y) do { } while (0) #endif #define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y)) static void _cache_sort(void **p1, void **p2) { void *tmp; if (*p1 > *p2) { tmp = *p2; *p2 = *p1; *p1 = tmp; } } static void cache_lock_all_buckets(void) { u_int i; for (i = 0; i < numbucketlocks; i++) rw_wlock(&bucketlocks[i]); } static void cache_unlock_all_buckets(void) { u_int i; for (i = 0; i < numbucketlocks; i++) rw_wunlock(&bucketlocks[i]); } static void cache_lock_all_vnodes(void) { u_int i; for (i = 0; i < numvnodelocks; i++) mtx_lock(&vnodelocks[i]); } static void cache_unlock_all_vnodes(void) { u_int i; for (i = 0; i < numvnodelocks; i++) mtx_unlock(&vnodelocks[i]); } static int cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) { cache_sort(&vlp1, &vlp2); MPASS(vlp2 != NULL); if (vlp1 != NULL) { if (!mtx_trylock(vlp1)) return (EAGAIN); } if (!mtx_trylock(vlp2)) { if (vlp1 != NULL) mtx_unlock(vlp1); return (EAGAIN); } return (0); } static void cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) { MPASS(vlp1 != NULL || vlp2 != NULL); if (vlp1 != NULL) mtx_unlock(vlp1); if (vlp2 != NULL) mtx_unlock(vlp2); } static int sysctl_nchstats(SYSCTL_HANDLER_ARGS) { struct nchstats snap; if (req->oldptr == NULL) return (SYSCTL_OUT(req, 0, sizeof(snap))); snap = nchstats; snap.ncs_goodhits = counter_u64_fetch(numposhits); snap.ncs_neghits = counter_u64_fetch(numneghits); snap.ncs_badhits = counter_u64_fetch(numposzaps) + counter_u64_fetch(numnegzaps); snap.ncs_miss = counter_u64_fetch(nummisszap) + counter_u64_fetch(nummiss); return (SYSCTL_OUT(req, &snap, sizeof(snap))); } SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", "VFS cache effectiveness statistics"); #ifdef DIAGNOSTIC /* * Grab an atomic snapshot of the name cache hash chain lengths */ static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); static int sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) { struct nchashhead *ncpp; struct namecache *ncp; int i, error, n_nchash, *cntbuf; retry: n_nchash = nchash + 1; /* nchash is max index, not count */ if (req->oldptr == NULL) return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); cache_lock_all_buckets(); if (n_nchash != nchash + 1) { cache_unlock_all_buckets(); free(cntbuf, M_TEMP); goto retry; } /* Scan hash tables counting entries */ for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) LIST_FOREACH(ncp, ncpp, nc_hash) cntbuf[i]++; cache_unlock_all_buckets(); for (error = 0, i = 0; i < n_nchash; i++) if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) break; free(cntbuf, M_TEMP); return (error); } SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); static int sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) { int error; struct nchashhead *ncpp; struct namecache *ncp; int n_nchash; int count, maxlength, used, pct; if (!req->oldptr) return SYSCTL_OUT(req, 0, 4 * sizeof(int)); cache_lock_all_buckets(); n_nchash = nchash + 1; /* nchash is max index, not count */ used = 0; maxlength = 0; /* Scan hash tables for applicable entries */ for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { count = 0; LIST_FOREACH(ncp, ncpp, nc_hash) { count++; } if (count) used++; if (maxlength < count) maxlength = count; } n_nchash = nchash + 1; cache_unlock_all_buckets(); pct = (used * 100) / (n_nchash / 100); error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); if (error) return (error); error = SYSCTL_OUT(req, &used, sizeof(used)); if (error) return (error); error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); if (error) return (error); error = SYSCTL_OUT(req, &pct, sizeof(pct)); if (error) return (error); return (0); } SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); #endif /* * Negative entries management * * A variation of LRU scheme is used. New entries are hashed into one of * numneglists cold lists. Entries get promoted to the hot list on first hit. * Partial LRU for the hot list is maintained by requeueing them every * ncneghitsrequeue hits. * * The shrinker will demote hot list head and evict from the cold list in a * round-robin manner. */ static void cache_negative_hit(struct namecache *ncp) { struct neglist *neglist; u_int hits; MPASS(ncp->nc_flag & NCF_NEGATIVE); hits = atomic_fetchadd_int(&ncp->nc_neghits, 1); if (ncp->nc_flag & NCF_HOTNEGATIVE) { if ((hits % ncneghitsrequeue) != 0) return; mtx_lock(&ncneg_hot.nl_lock); if (ncp->nc_flag & NCF_HOTNEGATIVE) { TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); mtx_unlock(&ncneg_hot.nl_lock); return; } /* * The shrinker cleared the flag and removed the entry from * the hot list. Put it back. */ } else { mtx_lock(&ncneg_hot.nl_lock); } neglist = NCP2NEGLIST(ncp); mtx_lock(&neglist->nl_lock); if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); ncp->nc_flag |= NCF_HOTNEGATIVE; } mtx_unlock(&neglist->nl_lock); mtx_unlock(&ncneg_hot.nl_lock); } static void cache_negative_insert(struct namecache *ncp, bool neg_locked) { struct neglist *neglist; MPASS(ncp->nc_flag & NCF_NEGATIVE); cache_assert_bucket_locked(ncp, RA_WLOCKED); neglist = NCP2NEGLIST(ncp); if (!neg_locked) { mtx_lock(&neglist->nl_lock); } else { mtx_assert(&neglist->nl_lock, MA_OWNED); } TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); if (!neg_locked) mtx_unlock(&neglist->nl_lock); atomic_add_rel_long(&numneg, 1); } static void cache_negative_remove(struct namecache *ncp, bool neg_locked) { struct neglist *neglist; bool hot_locked = false; bool list_locked = false; MPASS(ncp->nc_flag & NCF_NEGATIVE); cache_assert_bucket_locked(ncp, RA_WLOCKED); neglist = NCP2NEGLIST(ncp); if (!neg_locked) { if (ncp->nc_flag & NCF_HOTNEGATIVE) { hot_locked = true; mtx_lock(&ncneg_hot.nl_lock); if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { list_locked = true; mtx_lock(&neglist->nl_lock); } } else { list_locked = true; mtx_lock(&neglist->nl_lock); } } if (ncp->nc_flag & NCF_HOTNEGATIVE) { mtx_assert(&ncneg_hot.nl_lock, MA_OWNED); TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); } else { mtx_assert(&neglist->nl_lock, MA_OWNED); TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); } if (list_locked) mtx_unlock(&neglist->nl_lock); if (hot_locked) mtx_unlock(&ncneg_hot.nl_lock); atomic_subtract_rel_long(&numneg, 1); } static void cache_negative_shrink_select(int start, struct namecache **ncpp, struct neglist **neglistpp) { struct neglist *neglist; struct namecache *ncp; int i; *ncpp = ncp = NULL; neglist = NULL; for (i = start; i < numneglists; i++) { neglist = &neglists[i]; if (TAILQ_FIRST(&neglist->nl_list) == NULL) continue; mtx_lock(&neglist->nl_lock); ncp = TAILQ_FIRST(&neglist->nl_list); if (ncp != NULL) break; mtx_unlock(&neglist->nl_lock); } *neglistpp = neglist; *ncpp = ncp; } static void cache_negative_zap_one(void) { struct namecache *ncp, *ncp2; struct neglist *neglist; struct mtx *dvlp; struct rwlock *blp; if (!mtx_trylock(&ncneg_shrink_lock)) return; mtx_lock(&ncneg_hot.nl_lock); ncp = TAILQ_FIRST(&ncneg_hot.nl_list); if (ncp != NULL) { neglist = NCP2NEGLIST(ncp); mtx_lock(&neglist->nl_lock); TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); ncp->nc_flag &= ~NCF_HOTNEGATIVE; mtx_unlock(&neglist->nl_lock); } cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); shrink_list_turn++; if (shrink_list_turn == numneglists) shrink_list_turn = 0; if (ncp == NULL && shrink_list_turn == 0) cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); if (ncp == NULL) { mtx_unlock(&ncneg_hot.nl_lock); goto out; } MPASS(ncp->nc_flag & NCF_NEGATIVE); dvlp = VP2VNODELOCK(ncp->nc_dvp); blp = NCP2BUCKETLOCK(ncp); mtx_unlock(&neglist->nl_lock); mtx_unlock(&ncneg_hot.nl_lock); mtx_lock(dvlp); rw_wlock(blp); mtx_lock(&neglist->nl_lock); ncp2 = TAILQ_FIRST(&neglist->nl_list); if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) { ncp = NULL; goto out_unlock_all; } SDT_PROBE3(vfs, namecache, shrink_negative, done, ncp->nc_dvp, ncp->nc_name, ncp->nc_neghits); cache_zap_locked(ncp, true); out_unlock_all: mtx_unlock(&neglist->nl_lock); rw_wunlock(blp); mtx_unlock(dvlp); out: mtx_unlock(&ncneg_shrink_lock); cache_free(ncp); } /* * cache_zap_locked(): * * Removes a namecache entry from cache, whether it contains an actual * pointer to a vnode or if it is just a negative cache entry. */ static void cache_zap_locked(struct namecache *ncp, bool neg_locked) { if (!(ncp->nc_flag & NCF_NEGATIVE)) cache_assert_vnode_locked(ncp->nc_vp); cache_assert_vnode_locked(ncp->nc_dvp); cache_assert_bucket_locked(ncp, RA_WLOCKED); CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp); if (!(ncp->nc_flag & NCF_NEGATIVE)) { SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, ncp->nc_name, ncp->nc_vp); } else { SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp, ncp->nc_name, ncp->nc_neghits); } LIST_REMOVE(ncp, nc_hash); if (!(ncp->nc_flag & NCF_NEGATIVE)) { TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); if (ncp == ncp->nc_vp->v_cache_dd) ncp->nc_vp->v_cache_dd = NULL; } else { cache_negative_remove(ncp, neg_locked); } if (ncp->nc_flag & NCF_ISDOTDOT) { if (ncp == ncp->nc_dvp->v_cache_dd) ncp->nc_dvp->v_cache_dd = NULL; } else { LIST_REMOVE(ncp, nc_src); if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { ncp->nc_flag |= NCF_DVDROP; atomic_subtract_rel_long(&numcachehv, 1); } } atomic_subtract_rel_long(&numcache, 1); } static void cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) { struct rwlock *blp; MPASS(ncp->nc_dvp == vp); MPASS(ncp->nc_flag & NCF_NEGATIVE); cache_assert_vnode_locked(vp); blp = NCP2BUCKETLOCK(ncp); rw_wlock(blp); cache_zap_locked(ncp, false); rw_wunlock(blp); } static bool cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, struct mtx **vlpp) { struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; struct rwlock *blp; MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); cache_assert_vnode_locked(vp); if (ncp->nc_flag & NCF_NEGATIVE) { if (*vlpp != NULL) { mtx_unlock(*vlpp); *vlpp = NULL; } cache_zap_negative_locked_vnode_kl(ncp, vp); return (true); } pvlp = VP2VNODELOCK(vp); blp = NCP2BUCKETLOCK(ncp); vlp1 = VP2VNODELOCK(ncp->nc_dvp); vlp2 = VP2VNODELOCK(ncp->nc_vp); if (*vlpp == vlp1 || *vlpp == vlp2) { to_unlock = *vlpp; *vlpp = NULL; } else { if (*vlpp != NULL) { mtx_unlock(*vlpp); *vlpp = NULL; } cache_sort(&vlp1, &vlp2); if (vlp1 == pvlp) { mtx_lock(vlp2); to_unlock = vlp2; } else { if (!mtx_trylock(vlp1)) goto out_relock; to_unlock = vlp1; } } rw_wlock(blp); cache_zap_locked(ncp, false); rw_wunlock(blp); if (to_unlock != NULL) mtx_unlock(to_unlock); return (true); out_relock: mtx_unlock(vlp2); mtx_lock(vlp1); mtx_lock(vlp2); MPASS(*vlpp == NULL); *vlpp = vlp1; return (false); } static int cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) { struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; struct rwlock *blp; int error = 0; MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); cache_assert_vnode_locked(vp); pvlp = VP2VNODELOCK(vp); if (ncp->nc_flag & NCF_NEGATIVE) { cache_zap_negative_locked_vnode_kl(ncp, vp); goto out; } blp = NCP2BUCKETLOCK(ncp); vlp1 = VP2VNODELOCK(ncp->nc_dvp); vlp2 = VP2VNODELOCK(ncp->nc_vp); cache_sort(&vlp1, &vlp2); if (vlp1 == pvlp) { mtx_lock(vlp2); to_unlock = vlp2; } else { if (!mtx_trylock(vlp1)) { error = EAGAIN; goto out; } to_unlock = vlp1; } rw_wlock(blp); cache_zap_locked(ncp, false); rw_wunlock(blp); mtx_unlock(to_unlock); out: mtx_unlock(pvlp); return (error); } static int cache_zap_wlocked_bucket(struct namecache *ncp, struct rwlock *blp) { struct mtx *dvlp, *vlp; cache_assert_bucket_locked(ncp, RA_WLOCKED); dvlp = VP2VNODELOCK(ncp->nc_dvp); vlp = NULL; if (!(ncp->nc_flag & NCF_NEGATIVE)) vlp = VP2VNODELOCK(ncp->nc_vp); if (cache_trylock_vnodes(dvlp, vlp) == 0) { cache_zap_locked(ncp, false); rw_wunlock(blp); cache_unlock_vnodes(dvlp, vlp); return (0); } rw_wunlock(blp); return (EAGAIN); } static int cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp) { struct mtx *dvlp, *vlp; cache_assert_bucket_locked(ncp, RA_RLOCKED); dvlp = VP2VNODELOCK(ncp->nc_dvp); vlp = NULL; if (!(ncp->nc_flag & NCF_NEGATIVE)) vlp = VP2VNODELOCK(ncp->nc_vp); if (cache_trylock_vnodes(dvlp, vlp) == 0) { rw_runlock(blp); rw_wlock(blp); cache_zap_locked(ncp, false); rw_wunlock(blp); cache_unlock_vnodes(dvlp, vlp); return (0); } rw_runlock(blp); return (EAGAIN); } static int cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, struct mtx **vlpp1, struct mtx **vlpp2) { struct mtx *dvlp, *vlp; cache_assert_bucket_locked(ncp, RA_WLOCKED); dvlp = VP2VNODELOCK(ncp->nc_dvp); vlp = NULL; if (!(ncp->nc_flag & NCF_NEGATIVE)) vlp = VP2VNODELOCK(ncp->nc_vp); cache_sort(&dvlp, &vlp); if (*vlpp1 == dvlp && *vlpp2 == vlp) { cache_zap_locked(ncp, false); cache_unlock_vnodes(dvlp, vlp); *vlpp1 = NULL; *vlpp2 = NULL; return (0); } if (*vlpp1 != NULL) mtx_unlock(*vlpp1); if (*vlpp2 != NULL) mtx_unlock(*vlpp2); *vlpp1 = NULL; *vlpp2 = NULL; if (cache_trylock_vnodes(dvlp, vlp) == 0) { cache_zap_locked(ncp, false); cache_unlock_vnodes(dvlp, vlp); return (0); } rw_wunlock(blp); *vlpp1 = dvlp; *vlpp2 = vlp; if (*vlpp1 != NULL) mtx_lock(*vlpp1); mtx_lock(*vlpp2); rw_wlock(blp); return (EAGAIN); } static void cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) { if (blp != NULL) { rw_runlock(blp); } else { mtx_unlock(vlp); } } static int __noinline cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, struct timespec *tsp, int *ticksp) { int ltype; *vpp = dvp; CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", dvp, cnp->cn_nameptr); counter_u64_add(dothits, 1); SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); if (tsp != NULL) timespecclear(tsp); if (ticksp != NULL) *ticksp = ticks; vrefact(*vpp); /* * When we lookup "." we still can be asked to lock it * differently... */ ltype = cnp->cn_lkflags & LK_TYPE_MASK; if (ltype != VOP_ISLOCKED(*vpp)) { if (ltype == LK_EXCLUSIVE) { vn_lock(*vpp, LK_UPGRADE | LK_RETRY); if ((*vpp)->v_iflag & VI_DOOMED) { /* forced unmount */ vrele(*vpp); *vpp = NULL; return (ENOENT); } } else vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); } return (-1); } /* * Lookup an entry in the cache * * Lookup is called with dvp pointing to the directory to search, * cnp pointing to the name of the entry being sought. If the lookup * succeeds, the vnode is returned in *vpp, and a status of -1 is * returned. If the lookup determines that the name does not exist * (negative caching), a status of ENOENT is returned. If the lookup * fails, a status of zero is returned. If the directory vnode is * recycled out from under us due to a forced unmount, a status of * ENOENT is returned. * * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is * unlocked. If we're looking up . an extra ref is taken, but the lock is * not recursively acquired. */ static __noinline int cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, struct timespec *tsp, int *ticksp) { struct namecache *ncp; struct rwlock *blp; struct mtx *dvlp, *dvlp2; uint32_t hash; int error; if (cnp->cn_namelen == 2 && cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { counter_u64_add(dotdothits, 1); dvlp = VP2VNODELOCK(dvp); dvlp2 = NULL; mtx_lock(dvlp); retry_dotdot: ncp = dvp->v_cache_dd; if (ncp == NULL) { SDT_PROBE3(vfs, namecache, lookup, miss, dvp, "..", NULL); mtx_unlock(dvlp); if (dvlp2 != NULL) mtx_unlock(dvlp2); return (0); } if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { if (ncp->nc_dvp != dvp) panic("dvp %p v_cache_dd %p\n", dvp, ncp); if (!cache_zap_locked_vnode_kl2(ncp, dvp, &dvlp2)) goto retry_dotdot; MPASS(dvp->v_cache_dd == NULL); mtx_unlock(dvlp); if (dvlp2 != NULL) mtx_unlock(dvlp2); cache_free(ncp); } else { dvp->v_cache_dd = NULL; mtx_unlock(dvlp); if (dvlp2 != NULL) mtx_unlock(dvlp2); } return (0); } hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); blp = HASH2BUCKETLOCK(hash); retry: if (LIST_EMPTY(NCHHASH(hash))) goto out_no_entry; rw_wlock(blp); LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { counter_u64_add(numchecks, 1); if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) break; } /* We failed to find an entry */ if (ncp == NULL) { rw_wunlock(blp); goto out_no_entry; } counter_u64_add(numposzaps, 1); error = cache_zap_wlocked_bucket(ncp, blp); if (error != 0) { zap_and_exit_bucket_fail++; cache_maybe_yield(); goto retry; } cache_free(ncp); return (0); out_no_entry: SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL); counter_u64_add(nummisszap, 1); return (0); } int cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, struct timespec *tsp, int *ticksp) { struct namecache_ts *ncp_ts; struct namecache *ncp; struct rwlock *blp; struct mtx *dvlp; uint32_t hash; int error, ltype; if (__predict_false(!doingcache)) { cnp->cn_flags &= ~MAKEENTRY; return (0); } counter_u64_add(numcalls, 1); if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.')) return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); if ((cnp->cn_flags & MAKEENTRY) == 0) return (cache_lookup_nomakeentry(dvp, vpp, cnp, tsp, ticksp)); retry: blp = NULL; dvlp = NULL; error = 0; if (cnp->cn_namelen == 2 && cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { counter_u64_add(dotdothits, 1); dvlp = VP2VNODELOCK(dvp); mtx_lock(dvlp); ncp = dvp->v_cache_dd; if (ncp == NULL) { SDT_PROBE3(vfs, namecache, lookup, miss, dvp, "..", NULL); mtx_unlock(dvlp); return (0); } if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { if (ncp->nc_flag & NCF_NEGATIVE) *vpp = NULL; else *vpp = ncp->nc_vp; } else *vpp = ncp->nc_dvp; /* Return failure if negative entry was found. */ if (*vpp == NULL) goto negative_success; CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", dvp, cnp->cn_nameptr, *vpp); SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", *vpp); cache_out_ts(ncp, tsp, ticksp); if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == NCF_DTS && tsp != NULL) { ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); *tsp = ncp_ts->nc_dotdottime; } goto success; } hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); blp = HASH2BUCKETLOCK(hash); rw_rlock(blp); LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { counter_u64_add(numchecks, 1); if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) break; } /* We failed to find an entry */ if (ncp == NULL) { rw_runlock(blp); SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL); counter_u64_add(nummiss, 1); return (0); } /* We found a "positive" match, return the vnode */ if (!(ncp->nc_flag & NCF_NEGATIVE)) { counter_u64_add(numposhits, 1); *vpp = ncp->nc_vp; CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", dvp, cnp->cn_nameptr, *vpp, ncp); SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp); cache_out_ts(ncp, tsp, ticksp); goto success; } negative_success: /* We found a negative match, and want to create it, so purge */ if (cnp->cn_nameiop == CREATE) { counter_u64_add(numnegzaps, 1); goto zap_and_exit; } counter_u64_add(numneghits, 1); cache_negative_hit(ncp); if (ncp->nc_flag & NCF_WHITE) cnp->cn_flags |= ISWHITEOUT; SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name); cache_out_ts(ncp, tsp, ticksp); cache_lookup_unlock(blp, dvlp); return (ENOENT); success: /* * On success we return a locked and ref'd vnode as per the lookup * protocol. */ MPASS(dvp != *vpp); ltype = 0; /* silence gcc warning */ if (cnp->cn_flags & ISDOTDOT) { ltype = VOP_ISLOCKED(dvp); VOP_UNLOCK(dvp, 0); } vhold(*vpp); cache_lookup_unlock(blp, dvlp); error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); if (cnp->cn_flags & ISDOTDOT) { vn_lock(dvp, ltype | LK_RETRY); if (dvp->v_iflag & VI_DOOMED) { if (error == 0) vput(*vpp); *vpp = NULL; return (ENOENT); } } if (error) { *vpp = NULL; goto retry; } if ((cnp->cn_flags & ISLASTCN) && (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); } return (-1); zap_and_exit: if (blp != NULL) error = cache_zap_rlocked_bucket(ncp, blp); else error = cache_zap_locked_vnode(ncp, dvp); if (error != 0) { zap_and_exit_bucket_fail++; cache_maybe_yield(); goto retry; } cache_free(ncp); return (0); } struct celockstate { struct mtx *vlp[3]; struct rwlock *blp[2]; }; CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); static inline void cache_celockstate_init(struct celockstate *cel) { bzero(cel, sizeof(*cel)); } static void cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, struct vnode *dvp) { struct mtx *vlp1, *vlp2; MPASS(cel->vlp[0] == NULL); MPASS(cel->vlp[1] == NULL); MPASS(cel->vlp[2] == NULL); MPASS(vp != NULL || dvp != NULL); vlp1 = VP2VNODELOCK(vp); vlp2 = VP2VNODELOCK(dvp); cache_sort(&vlp1, &vlp2); if (vlp1 != NULL) { mtx_lock(vlp1); cel->vlp[0] = vlp1; } mtx_lock(vlp2); cel->vlp[1] = vlp2; } static void cache_unlock_vnodes_cel(struct celockstate *cel) { MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); if (cel->vlp[0] != NULL) mtx_unlock(cel->vlp[0]); if (cel->vlp[1] != NULL) mtx_unlock(cel->vlp[1]); if (cel->vlp[2] != NULL) mtx_unlock(cel->vlp[2]); } static bool cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) { struct mtx *vlp; bool ret; cache_assert_vlp_locked(cel->vlp[0]); cache_assert_vlp_locked(cel->vlp[1]); MPASS(cel->vlp[2] == NULL); MPASS(vp != NULL); vlp = VP2VNODELOCK(vp); ret = true; if (vlp >= cel->vlp[1]) { mtx_lock(vlp); } else { if (mtx_trylock(vlp)) goto out; cache_lock_vnodes_cel_3_failures++; cache_unlock_vnodes_cel(cel); if (vlp < cel->vlp[0]) { mtx_lock(vlp); mtx_lock(cel->vlp[0]); mtx_lock(cel->vlp[1]); } else { if (cel->vlp[0] != NULL) mtx_lock(cel->vlp[0]); mtx_lock(vlp); mtx_lock(cel->vlp[1]); } ret = false; } out: cel->vlp[2] = vlp; return (ret); } static void cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, struct rwlock *blp2) { MPASS(cel->blp[0] == NULL); MPASS(cel->blp[1] == NULL); cache_sort(&blp1, &blp2); if (blp1 != NULL) { rw_wlock(blp1); cel->blp[0] = blp1; } rw_wlock(blp2); cel->blp[1] = blp2; } static void cache_unlock_buckets_cel(struct celockstate *cel) { if (cel->blp[0] != NULL) rw_wunlock(cel->blp[0]); rw_wunlock(cel->blp[1]); } /* * Lock part of the cache affected by the insertion. * * This means vnodelocks for dvp, vp and the relevant bucketlock. * However, insertion can result in removal of an old entry. In this * case we have an additional vnode and bucketlock pair to lock. If the * entry is negative, ncelock is locked instead of the vnode. * * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while * preserving the locking order (smaller address first). */ static void cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, uint32_t hash) { struct namecache *ncp; struct rwlock *blps[2]; blps[0] = HASH2BUCKETLOCK(hash); for (;;) { blps[1] = NULL; cache_lock_vnodes_cel(cel, dvp, vp); if (vp == NULL || vp->v_type != VDIR) break; ncp = vp->v_cache_dd; if (ncp == NULL) break; if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) break; MPASS(ncp->nc_dvp == vp); blps[1] = NCP2BUCKETLOCK(ncp); if (ncp->nc_flag & NCF_NEGATIVE) break; if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) break; /* * All vnodes got re-locked. Re-validate the state and if * nothing changed we are done. Otherwise restart. */ if (ncp == vp->v_cache_dd && (ncp->nc_flag & NCF_ISDOTDOT) != 0 && blps[1] == NCP2BUCKETLOCK(ncp) && VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) break; cache_unlock_vnodes_cel(cel); cel->vlp[0] = NULL; cel->vlp[1] = NULL; cel->vlp[2] = NULL; } cache_lock_buckets_cel(cel, blps[0], blps[1]); } static void cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, uint32_t hash) { struct namecache *ncp; struct rwlock *blps[2]; blps[0] = HASH2BUCKETLOCK(hash); for (;;) { blps[1] = NULL; cache_lock_vnodes_cel(cel, dvp, vp); ncp = dvp->v_cache_dd; if (ncp == NULL) break; if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) break; MPASS(ncp->nc_dvp == dvp); blps[1] = NCP2BUCKETLOCK(ncp); if (ncp->nc_flag & NCF_NEGATIVE) break; if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) break; if (ncp == dvp->v_cache_dd && (ncp->nc_flag & NCF_ISDOTDOT) != 0 && blps[1] == NCP2BUCKETLOCK(ncp) && VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) break; cache_unlock_vnodes_cel(cel); cel->vlp[0] = NULL; cel->vlp[1] = NULL; cel->vlp[2] = NULL; } cache_lock_buckets_cel(cel, blps[0], blps[1]); } static void cache_enter_unlock(struct celockstate *cel) { cache_unlock_buckets_cel(cel); cache_unlock_vnodes_cel(cel); } /* * Add an entry to the cache. */ void cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, struct timespec *tsp, struct timespec *dtsp) { struct celockstate cel; struct namecache *ncp, *n2, *ndd; struct namecache_ts *ncp_ts, *n2_ts; struct nchashhead *ncpp; struct neglist *neglist; uint32_t hash; int flag; int len; bool neg_locked; int lnumcache; CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, ("cache_enter: Adding a doomed vnode")); VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, ("cache_enter: Doomed vnode used as src")); if (__predict_false(!doingcache)) return; /* * Avoid blowout in namecache entries. */ if (__predict_false(numcache >= desiredvnodes * ncsizefactor)) return; cache_celockstate_init(&cel); ndd = NULL; ncp_ts = NULL; flag = 0; if (cnp->cn_nameptr[0] == '.') { if (cnp->cn_namelen == 1) return; if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { len = cnp->cn_namelen; hash = cache_get_hash(cnp->cn_nameptr, len, dvp); cache_enter_lock_dd(&cel, dvp, vp, hash); /* * If dotdot entry already exists, just retarget it * to new parent vnode, otherwise continue with new * namecache entry allocation. */ if ((ncp = dvp->v_cache_dd) != NULL && ncp->nc_flag & NCF_ISDOTDOT) { KASSERT(ncp->nc_dvp == dvp, ("wrong isdotdot parent")); neg_locked = false; if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) { neglist = NCP2NEGLIST(ncp); mtx_lock(&ncneg_hot.nl_lock); mtx_lock(&neglist->nl_lock); neg_locked = true; } if (!(ncp->nc_flag & NCF_NEGATIVE)) { TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); } else { cache_negative_remove(ncp, true); } if (vp != NULL) { TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE); } else { ncp->nc_flag &= ~(NCF_HOTNEGATIVE); ncp->nc_flag |= NCF_NEGATIVE; cache_negative_insert(ncp, true); } if (neg_locked) { mtx_unlock(&neglist->nl_lock); mtx_unlock(&ncneg_hot.nl_lock); } ncp->nc_vp = vp; cache_enter_unlock(&cel); return; } dvp->v_cache_dd = NULL; cache_enter_unlock(&cel); cache_celockstate_init(&cel); SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); flag = NCF_ISDOTDOT; } } /* * Calculate the hash key and setup as much of the new * namecache entry as possible before acquiring the lock. */ ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); ncp->nc_flag = flag; ncp->nc_vp = vp; if (vp == NULL) ncp->nc_flag |= NCF_NEGATIVE; ncp->nc_dvp = dvp; if (tsp != NULL) { ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); ncp_ts->nc_time = *tsp; ncp_ts->nc_ticks = ticks; ncp_ts->nc_nc.nc_flag |= NCF_TS; if (dtsp != NULL) { ncp_ts->nc_dotdottime = *dtsp; ncp_ts->nc_nc.nc_flag |= NCF_DTS; } } len = ncp->nc_nlen = cnp->cn_namelen; hash = cache_get_hash(cnp->cn_nameptr, len, dvp); strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1); cache_enter_lock(&cel, dvp, vp, hash); /* * See if this vnode or negative entry is already in the cache * with this name. This can happen with concurrent lookups of * the same path name. */ ncpp = NCHHASH(hash); LIST_FOREACH(n2, ncpp, nc_hash) { if (n2->nc_dvp == dvp && n2->nc_nlen == cnp->cn_namelen && !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { if (tsp != NULL) { KASSERT((n2->nc_flag & NCF_TS) != 0, ("no NCF_TS")); n2_ts = __containerof(n2, struct namecache_ts, nc_nc); n2_ts->nc_time = ncp_ts->nc_time; n2_ts->nc_ticks = ncp_ts->nc_ticks; if (dtsp != NULL) { n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime; if (ncp->nc_flag & NCF_NEGATIVE) mtx_lock(&ncneg_hot.nl_lock); n2_ts->nc_nc.nc_flag |= NCF_DTS; if (ncp->nc_flag & NCF_NEGATIVE) mtx_unlock(&ncneg_hot.nl_lock); } } goto out_unlock_free; } } if (flag == NCF_ISDOTDOT) { /* * See if we are trying to add .. entry, but some other lookup * has populated v_cache_dd pointer already. */ if (dvp->v_cache_dd != NULL) goto out_unlock_free; KASSERT(vp == NULL || vp->v_type == VDIR, ("wrong vnode type %p", vp)); dvp->v_cache_dd = ncp; } if (vp != NULL) { if (vp->v_type == VDIR) { if (flag != NCF_ISDOTDOT) { /* * For this case, the cache entry maps both the * directory name in it and the name ".." for the * directory's parent. */ if ((ndd = vp->v_cache_dd) != NULL) { if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) cache_zap_locked(ndd, false); else ndd = NULL; } vp->v_cache_dd = ncp; } } else { vp->v_cache_dd = NULL; } } if (flag != NCF_ISDOTDOT) { if (LIST_EMPTY(&dvp->v_cache_src)) { vhold(dvp); atomic_add_rel_long(&numcachehv, 1); } LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); } /* * Insert the new namecache entry into the appropriate chain * within the cache entries table. */ LIST_INSERT_HEAD(ncpp, ncp, nc_hash); /* * If the entry is "negative", we place it into the * "negative" cache queue, otherwise, we place it into the * destination vnode's cache entries queue. */ if (vp != NULL) { TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name, vp); } else { if (cnp->cn_flags & ISWHITEOUT) ncp->nc_flag |= NCF_WHITE; cache_negative_insert(ncp, false); SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, ncp->nc_name); } cache_enter_unlock(&cel); lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; if (numneg * ncnegfactor > lnumcache) cache_negative_zap_one(); cache_free(ndd); return; out_unlock_free: cache_enter_unlock(&cel); cache_free(ncp); return; } static u_int cache_roundup_2(u_int val) { u_int res; for (res = 1; res <= val; res <<= 1) continue; return (res); } /* * Name cache initialization, from vfs_init() when we are booting */ static void nchinit(void *dummy __unused) { u_int i; cache_zone_small = uma_zcreate("S VFS Cache", sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), UMA_ZONE_ZINIT); cache_zone_small_ts = uma_zcreate("STS VFS Cache", sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), UMA_ZONE_ZINIT); cache_zone_large = uma_zcreate("L VFS Cache", sizeof(struct namecache) + NAME_MAX + 1, NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), UMA_ZONE_ZINIT); cache_zone_large_ts = uma_zcreate("LTS VFS Cache", sizeof(struct namecache_ts) + NAME_MAX + 1, NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), UMA_ZONE_ZINIT); nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1; if (ncbuckethash > nchash) ncbuckethash = nchash; bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, M_WAITOK | M_ZERO); for (i = 0; i < numbucketlocks; i++) rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1; vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, M_WAITOK | M_ZERO); for (i = 0; i < numvnodelocks; i++) mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); ncpurgeminvnodes = numbucketlocks; ncneghash = 3; neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, M_WAITOK | M_ZERO); for (i = 0; i < numneglists; i++) { mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); TAILQ_INIT(&neglists[i].nl_list); } mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); TAILQ_INIT(&ncneg_hot.nl_list); mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); numcalls = counter_u64_alloc(M_WAITOK); dothits = counter_u64_alloc(M_WAITOK); dotdothits = counter_u64_alloc(M_WAITOK); numchecks = counter_u64_alloc(M_WAITOK); nummiss = counter_u64_alloc(M_WAITOK); nummisszap = counter_u64_alloc(M_WAITOK); numposzaps = counter_u64_alloc(M_WAITOK); numposhits = counter_u64_alloc(M_WAITOK); numnegzaps = counter_u64_alloc(M_WAITOK); numneghits = counter_u64_alloc(M_WAITOK); numfullpathcalls = counter_u64_alloc(M_WAITOK); numfullpathfail1 = counter_u64_alloc(M_WAITOK); numfullpathfail2 = counter_u64_alloc(M_WAITOK); numfullpathfail4 = counter_u64_alloc(M_WAITOK); numfullpathfound = counter_u64_alloc(M_WAITOK); } SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); void cache_changesize(int newmaxvnodes) { struct nchashhead *new_nchashtbl, *old_nchashtbl; u_long new_nchash, old_nchash; struct namecache *ncp; uint32_t hash; int i; newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); if (newmaxvnodes < numbucketlocks) newmaxvnodes = numbucketlocks; new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); /* If same hash table size, nothing to do */ if (nchash == new_nchash) { free(new_nchashtbl, M_VFSCACHE); return; } /* * Move everything from the old hash table to the new table. * None of the namecache entries in the table can be removed * because to do so, they have to be removed from the hash table. */ cache_lock_all_vnodes(); cache_lock_all_buckets(); old_nchashtbl = nchashtbl; old_nchash = nchash; nchashtbl = new_nchashtbl; nchash = new_nchash; for (i = 0; i <= old_nchash; i++) { while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); LIST_REMOVE(ncp, nc_hash); LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); } } cache_unlock_all_buckets(); cache_unlock_all_vnodes(); free(old_nchashtbl, M_VFSCACHE); } /* * Invalidate all entries to a particular vnode. */ void cache_purge(struct vnode *vp) { TAILQ_HEAD(, namecache) ncps; struct namecache *ncp, *nnp; struct mtx *vlp, *vlp2; CTR1(KTR_VFS, "cache_purge(%p)", vp); SDT_PROBE1(vfs, namecache, purge, done, vp); if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && vp->v_cache_dd == NULL) return; TAILQ_INIT(&ncps); vlp = VP2VNODELOCK(vp); vlp2 = NULL; mtx_lock(vlp); retry: while (!LIST_EMPTY(&vp->v_cache_src)) { ncp = LIST_FIRST(&vp->v_cache_src); if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) goto retry; TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); } while (!TAILQ_EMPTY(&vp->v_cache_dst)) { ncp = TAILQ_FIRST(&vp->v_cache_dst); if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) goto retry; TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); } ncp = vp->v_cache_dd; if (ncp != NULL) { KASSERT(ncp->nc_flag & NCF_ISDOTDOT, ("lost dotdot link")); if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) goto retry; TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); } KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); mtx_unlock(vlp); if (vlp2 != NULL) mtx_unlock(vlp2); TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { cache_free(ncp); } } /* * Invalidate all negative entries for a particular directory vnode. */ void cache_purge_negative(struct vnode *vp) { TAILQ_HEAD(, namecache) ncps; struct namecache *ncp, *nnp; struct mtx *vlp; CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); SDT_PROBE1(vfs, namecache, purge_negative, done, vp); if (LIST_EMPTY(&vp->v_cache_src)) return; TAILQ_INIT(&ncps); vlp = VP2VNODELOCK(vp); mtx_lock(vlp); LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { if (!(ncp->nc_flag & NCF_NEGATIVE)) continue; cache_zap_negative_locked_vnode_kl(ncp, vp); TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); } mtx_unlock(vlp); TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { cache_free(ncp); } } /* * Flush all entries referencing a particular filesystem. */ void cache_purgevfs(struct mount *mp, bool force) { TAILQ_HEAD(, namecache) ncps; struct mtx *vlp1, *vlp2; struct rwlock *blp; struct nchashhead *bucket; struct namecache *ncp, *nnp; u_long i, j, n_nchash; int error; /* Scan hash tables for applicable entries */ SDT_PROBE1(vfs, namecache, purgevfs, done, mp); if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) return; TAILQ_INIT(&ncps); n_nchash = nchash + 1; vlp1 = vlp2 = NULL; for (i = 0; i < numbucketlocks; i++) { blp = (struct rwlock *)&bucketlocks[i]; rw_wlock(blp); for (j = i; j < n_nchash; j += numbucketlocks) { retry: bucket = &nchashtbl[j]; LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { cache_assert_bucket_locked(ncp, RA_WLOCKED); if (ncp->nc_dvp->v_mount != mp) continue; error = cache_zap_wlocked_bucket_kl(ncp, blp, &vlp1, &vlp2); if (error != 0) goto retry; TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); } } rw_wunlock(blp); if (vlp1 == NULL && vlp2 == NULL) cache_maybe_yield(); } if (vlp1 != NULL) mtx_unlock(vlp1); if (vlp2 != NULL) mtx_unlock(vlp2); TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { cache_free(ncp); } } /* * Perform canonical checks and cache lookup and pass on to filesystem * through the vop_cachedlookup only if needed. */ int vfs_cache_lookup(struct vop_lookup_args *ap) { struct vnode *dvp; int error; struct vnode **vpp = ap->a_vpp; struct componentname *cnp = ap->a_cnp; struct ucred *cred = cnp->cn_cred; int flags = cnp->cn_flags; struct thread *td = cnp->cn_thread; *vpp = NULL; dvp = ap->a_dvp; if (dvp->v_type != VDIR) return (ENOTDIR); if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) return (EROFS); error = VOP_ACCESS(dvp, VEXEC, cred, td); if (error) return (error); error = cache_lookup(dvp, vpp, cnp, NULL, NULL); if (error == 0) return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); if (error == -1) return (0); return (error); } /* * XXX All of these sysctls would probably be more productive dead. */ static int __read_mostly disablecwd; SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "Disable the getcwd syscall"); /* Implementation of the getcwd syscall. */ int sys___getcwd(struct thread *td, struct __getcwd_args *uap) { return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, MAXPATHLEN)); } int kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen, size_t path_max) { char *bp, *tmpbuf; struct filedesc *fdp; struct vnode *cdir, *rdir; int error; if (__predict_false(disablecwd)) return (ENODEV); if (__predict_false(buflen < 2)) return (EINVAL); if (buflen > path_max) buflen = path_max; tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); cdir = fdp->fd_cdir; vrefact(cdir); rdir = fdp->fd_rdir; vrefact(rdir); FILEDESC_SUNLOCK(fdp); error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); vrele(rdir); vrele(cdir); if (!error) { if (bufseg == UIO_SYSSPACE) bcopy(bp, buf, strlen(bp) + 1); else error = copyout(bp, buf, strlen(bp) + 1); #ifdef KTRACE if (KTRPOINT(curthread, KTR_NAMEI)) ktrnamei(bp); #endif } free(tmpbuf, M_TEMP); return (error); } /* * Thus begins the fullpath magic. */ static int __read_mostly disablefullpath; SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, "Disable the vn_fullpath function"); /* * Retrieve the full filesystem path that correspond to a vnode from the name * cache (if available) */ int vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) { char *buf; struct filedesc *fdp; struct vnode *rdir; int error; if (__predict_false(disablefullpath)) return (ENODEV); if (__predict_false(vn == NULL)) return (EINVAL); buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); rdir = fdp->fd_rdir; vrefact(rdir); FILEDESC_SUNLOCK(fdp); error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); vrele(rdir); if (!error) *freebuf = buf; else free(buf, M_TEMP); return (error); } /* * This function is similar to vn_fullpath, but it attempts to lookup the * pathname relative to the global root mount point. This is required for the * auditing sub-system, as audited pathnames must be absolute, relative to the * global root mount point. */ int vn_fullpath_global(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) { char *buf; int error; if (__predict_false(disablefullpath)) return (ENODEV); if (__predict_false(vn == NULL)) return (EINVAL); buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); if (!error) *freebuf = buf; else free(buf, M_TEMP); return (error); } int vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) { struct vnode *dvp; struct namecache *ncp; struct mtx *vlp; int error; vlp = VP2VNODELOCK(*vp); mtx_lock(vlp); TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) break; } if (ncp != NULL) { if (*buflen < ncp->nc_nlen) { mtx_unlock(vlp); vrele(*vp); counter_u64_add(numfullpathfail4, 1); error = ENOMEM; SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); return (error); } *buflen -= ncp->nc_nlen; memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, ncp->nc_name, vp); dvp = *vp; *vp = ncp->nc_dvp; vref(*vp); mtx_unlock(vlp); vrele(dvp); return (0); } SDT_PROBE1(vfs, namecache, fullpath, miss, vp); mtx_unlock(vlp); vn_lock(*vp, LK_SHARED | LK_RETRY); error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); vput(*vp); if (error) { counter_u64_add(numfullpathfail2, 1); SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); return (error); } *vp = dvp; if (dvp->v_iflag & VI_DOOMED) { /* forced unmount */ vrele(dvp); error = ENOENT; SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); return (error); } /* * *vp has its use count incremented still. */ return (0); } /* * The magic behind kern___getcwd() and vn_fullpath(). */ static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, u_int buflen) { int error, slash_prefixed; #ifdef KDTRACE_HOOKS struct vnode *startvp = vp; #endif struct vnode *vp1; buflen--; buf[buflen] = '\0'; error = 0; slash_prefixed = 0; SDT_PROBE1(vfs, namecache, fullpath, entry, vp); counter_u64_add(numfullpathcalls, 1); vref(vp); if (vp->v_type != VDIR) { error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); if (error) return (error); if (buflen == 0) { vrele(vp); return (ENOMEM); } buf[--buflen] = '/'; slash_prefixed = 1; } while (vp != rdir && vp != rootvnode) { /* * The vp vnode must be already fully constructed, * since it is either found in namecache or obtained * from VOP_VPTOCNP(). We may test for VV_ROOT safely * without obtaining the vnode lock. */ if ((vp->v_vflag & VV_ROOT) != 0) { vn_lock(vp, LK_RETRY | LK_SHARED); /* * With the vnode locked, check for races with * unmount, forced or not. Note that we * already verified that vp is not equal to * the root vnode, which means that * mnt_vnodecovered can be NULL only for the * case of unmount. */ if ((vp->v_iflag & VI_DOOMED) != 0 || (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || vp1->v_mountedhere != vp->v_mount) { vput(vp); error = ENOENT; SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); break; } vref(vp1); vput(vp); vp = vp1; continue; } if (vp->v_type != VDIR) { vrele(vp); counter_u64_add(numfullpathfail1, 1); error = ENOTDIR; SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); break; } error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); if (error) break; if (buflen == 0) { vrele(vp); error = ENOMEM; SDT_PROBE3(vfs, namecache, fullpath, return, error, startvp, NULL); break; } buf[--buflen] = '/'; slash_prefixed = 1; } if (error) return (error); if (!slash_prefixed) { if (buflen == 0) { vrele(vp); counter_u64_add(numfullpathfail4, 1); SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, startvp, NULL); return (ENOMEM); } buf[--buflen] = '/'; } counter_u64_add(numfullpathfound, 1); vrele(vp); SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); *retbuf = buf + buflen; return (0); } struct vnode * vn_dir_dd_ino(struct vnode *vp) { struct namecache *ncp; struct vnode *ddvp; struct mtx *vlp; ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); vlp = VP2VNODELOCK(vp); mtx_lock(vlp); TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) continue; ddvp = ncp->nc_dvp; vhold(ddvp); mtx_unlock(vlp); if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) return (NULL); return (ddvp); } mtx_unlock(vlp); return (NULL); } int vn_commname(struct vnode *vp, char *buf, u_int buflen) { struct namecache *ncp; struct mtx *vlp; int l; vlp = VP2VNODELOCK(vp); mtx_lock(vlp); TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) break; if (ncp == NULL) { mtx_unlock(vlp); return (ENOENT); } l = min(ncp->nc_nlen, buflen - 1); memcpy(buf, ncp->nc_name, l); mtx_unlock(vlp); buf[l] = '\0'; return (0); } /* ABI compat shims for old kernel modules. */ #undef cache_enter void cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp); void cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) { cache_enter_time(dvp, vp, cnp, NULL, NULL); } /* * This function updates path string to vnode's full global path * and checks the size of the new path string against the pathlen argument. * * Requires a locked, referenced vnode. * Vnode is re-locked on success or ENODEV, otherwise unlocked. * * If sysctl debug.disablefullpath is set, ENODEV is returned, * vnode is left locked and path remain untouched. * * If vp is a directory, the call to vn_fullpath_global() always succeeds * because it falls back to the ".." lookup if the namecache lookup fails. */ int vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, u_int pathlen) { struct nameidata nd; struct vnode *vp1; char *rpath, *fbuf; int error; ASSERT_VOP_ELOCKED(vp, __func__); /* Return ENODEV if sysctl debug.disablefullpath==1 */ if (__predict_false(disablefullpath)) return (ENODEV); /* Construct global filesystem path from vp. */ VOP_UNLOCK(vp, 0); error = vn_fullpath_global(td, vp, &rpath, &fbuf); if (error != 0) { vrele(vp); return (error); } if (strlen(rpath) >= pathlen) { vrele(vp); error = ENAMETOOLONG; goto out; } /* * Re-lookup the vnode by path to detect a possible rename. * As a side effect, the vnode is relocked. * If vnode was renamed, return ENOENT. */ NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_SYSSPACE, path, td); error = namei(&nd); if (error != 0) { vrele(vp); goto out; } NDFREE(&nd, NDF_ONLY_PNBUF); vp1 = nd.ni_vp; vrele(vp); if (vp1 == vp) strcpy(path, rpath); else { vput(vp1); error = ENOENT; } out: free(fbuf, M_TEMP); return (error); } + +#ifdef DDB +static void +db_print_vpath(struct vnode *vp) +{ + + while (vp != NULL) { + db_printf("%p: ", vp); + if (vp == rootvnode) { + db_printf("/"); + vp = NULL; + } else { + if (vp->v_vflag & VV_ROOT) { + db_printf(""); + vp = vp->v_mount->mnt_vnodecovered; + } else { + struct namecache *ncp; + char *ncn; + int i; + + ncp = TAILQ_FIRST(&vp->v_cache_dst); + if (ncp != NULL) { + ncn = ncp->nc_name; + for (i = 0; i < ncp->nc_nlen; i++) + db_printf("%c", *ncn++); + vp = ncp->nc_dvp; + } else { + vp = NULL; + } + } + } + db_printf("\n"); + } + + return; +} + +DB_SHOW_COMMAND(vpath, db_show_vpath) +{ + struct vnode *vp; + + if (!have_addr) { + db_printf("usage: show vpath \n"); + return; + } + + vp = (struct vnode *)addr; + db_print_vpath(vp); +} + +#endif