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diff --git a/lib/libsys/rename.2 b/lib/libsys/rename.2
--- a/lib/libsys/rename.2
+++ b/lib/libsys/rename.2
@@ -143,6 +143,12 @@
.Fa to
exists, the request fails with the error
.Er EEXIST .
+.It Dv AT_RENAME_EXCHANGE
+Atomically exchange the files pointed to by the
+.Fa from
+and
+.Fa to
+names.
.El
.Sh RETURN VALUES
.Rv -std rename
diff --git a/sys/fs/tmpfs/tmpfs_vnops.c b/sys/fs/tmpfs/tmpfs_vnops.c
--- a/sys/fs/tmpfs/tmpfs_vnops.c
+++ b/sys/fs/tmpfs/tmpfs_vnops.c
@@ -962,6 +962,89 @@
return (error);
}
+static int
+tmpfs_rename_check_parent(struct tmpfs_mount *tmp, struct tmpfs_node *fdnode,
+ struct vnode *fvp, struct tmpfs_node *fnode, struct tmpfs_dirent *de,
+ struct tmpfs_node *tdnode, struct ucred *tcred)
+{
+ struct tmpfs_node *n;
+ int error;
+
+ TMPFS_NODE_LOCK(fnode);
+ error = tmpfs_access_locked(fvp, fnode, VWRITE, tcred);
+ TMPFS_NODE_UNLOCK(fnode);
+ if (error != 0)
+ return (error);
+
+ /*
+ * Ensure the target directory is not a child of the
+ * directory being moved. Otherwise, we'd end up
+ * with stale nodes.
+ *
+ * TMPFS_LOCK guaranties that no nodes are freed while
+ * traversing the list. Nodes can only be marked as
+ * removed: tn_parent == NULL.
+ */
+ n = tdnode;
+ TMPFS_LOCK(tmp);
+ TMPFS_NODE_LOCK(n);
+ while (n != n->tn_dir.tn_parent) {
+ struct tmpfs_node *parent;
+
+ if (n == fnode) {
+ TMPFS_NODE_UNLOCK(n);
+ TMPFS_UNLOCK(tmp);
+ return (EINVAL);
+ }
+ parent = n->tn_dir.tn_parent;
+ TMPFS_NODE_UNLOCK(n);
+ if (parent == NULL) {
+ n = NULL;
+ break;
+ }
+ TMPFS_NODE_LOCK(parent);
+ if (parent->tn_dir.tn_parent == NULL) {
+ TMPFS_NODE_UNLOCK(parent);
+ n = NULL;
+ break;
+ }
+ n = parent;
+ }
+ TMPFS_UNLOCK(tmp);
+ if (n == NULL)
+ return (EINVAL);
+
+ TMPFS_NODE_UNLOCK(n);
+
+ return (0);
+}
+
+static void
+tmpfs_rename_set_parent(struct tmpfs_node *fdnode, struct tmpfs_node *fnode,
+ struct tmpfs_dirent *de, struct tmpfs_node *tdnode)
+{
+ /* Adjust the parent pointer. */
+ TMPFS_VALIDATE_DIR(fnode);
+ TMPFS_NODE_LOCK(de->td_node);
+ de->td_node->tn_dir.tn_parent = tdnode;
+ TMPFS_NODE_UNLOCK(de->td_node);
+
+ /*
+ * As a result of changing the target of the '..'
+ * entry, the link count of the source and target
+ * directories has to be adjusted.
+ */
+ TMPFS_NODE_LOCK(tdnode);
+ TMPFS_ASSERT_LOCKED(tdnode);
+ tdnode->tn_links++;
+ TMPFS_NODE_UNLOCK(tdnode);
+
+ TMPFS_NODE_LOCK(fdnode);
+ TMPFS_ASSERT_LOCKED(fdnode);
+ fdnode->tn_links--;
+ TMPFS_NODE_UNLOCK(fdnode);
+}
+
static int
tmpfs_rename(struct vop_rename_args *v)
{
@@ -972,7 +1055,7 @@
struct vnode *tvp = v->a_tvp;
struct componentname *tcnp = v->a_tcnp;
char *newname;
- struct tmpfs_dirent *de;
+ struct tmpfs_dirent *de, *tde;
struct tmpfs_mount *tmp;
struct tmpfs_node *fdnode;
struct tmpfs_node *fnode;
@@ -980,8 +1063,11 @@
struct tmpfs_node *tdnode;
int error;
bool want_seqc_end;
+ bool exchange;
want_seqc_end = false;
+ newname = NULL;
+ error = 0;
/*
* Disallow cross-device renames.
@@ -993,16 +1079,15 @@
goto out;
}
- if ((v->a_flags & ~(AT_RENAME_NOREPLACE)) != 0) {
+ if ((v->a_flags & ~(AT_RENAME_NOREPLACE | AT_RENAME_EXCHANGE)) != 0) {
error = EOPNOTSUPP;
goto out;
}
/* If source and target are the same file, there is nothing to do. */
- if (fvp == tvp) {
- error = 0;
+ if (fvp == tvp)
goto out;
- }
+ exchange = (v->a_flags & AT_RENAME_EXCHANGE) != 0;
/*
* If we need to move the directory between entries, lock the
@@ -1055,6 +1140,8 @@
fdnode = VP_TO_TMPFS_DIR(fdvp);
fnode = VP_TO_TMPFS_NODE(fvp);
de = tmpfs_dir_lookup(fdnode, fnode, fcnp);
+ if (exchange)
+ tde = tmpfs_dir_lookup(tdnode, tnode, tcnp);
/*
* Entry can disappear before we lock fdvp.
@@ -1068,6 +1155,13 @@
goto out_locked;
}
MPASS(de->td_node == fnode);
+ if (exchange) {
+ if (tde == NULL) {
+ error = ENOENT;
+ goto out_locked;
+ }
+ MPASS(tde->td_node == tnode);
+ }
/*
* If re-naming a directory to another preexisting directory
@@ -1085,27 +1179,32 @@
goto out_locked;
}
- if (fnode->tn_type == VDIR && tnode->tn_type == VDIR) {
- if (tnode->tn_size != 0 &&
- ((tcnp->cn_flags & IGNOREWHITEOUT) == 0 ||
- tnode->tn_size > tnode->tn_dir.tn_wht_size)) {
- error = ENOTEMPTY;
+ if (!exchange) {
+ if (fnode->tn_type == VDIR && tnode->tn_type == VDIR) {
+ if (tnode->tn_size != 0 &&
+ ((tcnp->cn_flags & IGNOREWHITEOUT) == 0 ||
+ tnode->tn_size >
+ tnode->tn_dir.tn_wht_size)) {
+ error = ENOTEMPTY;
+ goto out_locked;
+ }
+ } else if (fnode->tn_type == VDIR &&
+ tnode->tn_type != VDIR) {
+ error = ENOTDIR;
goto out_locked;
+ } else if (fnode->tn_type != VDIR &&
+ tnode->tn_type == VDIR) {
+ error = EISDIR;
+ goto out_locked;
+ } else {
+ MPASS(fnode->tn_type != VDIR &&
+ tnode->tn_type != VDIR);
}
- } else if (fnode->tn_type == VDIR && tnode->tn_type != VDIR) {
- error = ENOTDIR;
- goto out_locked;
- } else if (fnode->tn_type != VDIR && tnode->tn_type == VDIR) {
- error = EISDIR;
- goto out_locked;
- } else {
- MPASS(fnode->tn_type != VDIR &&
- tnode->tn_type != VDIR);
}
}
- if ((fnode->tn_flags & (NOUNLINK | IMMUTABLE | APPEND))
- || (fdnode->tn_flags & (APPEND | IMMUTABLE))) {
+ if ((fnode->tn_flags & (NOUNLINK | IMMUTABLE | APPEND)) != 0 ||
+ (fdnode->tn_flags & (APPEND | IMMUTABLE)) != 0) {
error = EPERM;
goto out_locked;
}
@@ -1114,11 +1213,9 @@
* Ensure that we have enough memory to hold the new name, if it
* has to be changed.
*/
- if (fcnp->cn_namelen != tcnp->cn_namelen ||
- bcmp(fcnp->cn_nameptr, tcnp->cn_nameptr, fcnp->cn_namelen) != 0) {
+ if (!exchange && (fcnp->cn_namelen != tcnp->cn_namelen ||
+ bcmp(fcnp->cn_nameptr, tcnp->cn_nameptr, fcnp->cn_namelen) != 0))
newname = malloc(tcnp->cn_namelen, M_TMPFSNAME, M_WAITOK);
- } else
- newname = NULL;
/*
* If the node is being moved to another directory, we have to do
@@ -1129,87 +1226,45 @@
* In case we are moving a directory, we have to adjust its
* parent to point to the new parent.
*/
- if (de->td_node->tn_type == VDIR) {
- struct tmpfs_node *n;
-
- TMPFS_NODE_LOCK(fnode);
- error = tmpfs_access_locked(fvp, fnode, VWRITE,
- tcnp->cn_cred);
- TMPFS_NODE_UNLOCK(fnode);
- if (error) {
- if (newname != NULL)
- free(newname, M_TMPFSNAME);
+ if (fnode->tn_type == VDIR) {
+ error = tmpfs_rename_check_parent(tmp, fdnode, fvp,
+ fnode, de, tdnode, tcnp->cn_cred);
+ if (error != 0) {
+ free(newname, M_TMPFSNAME);
goto out_locked;
}
-
- /*
- * Ensure the target directory is not a child of the
- * directory being moved. Otherwise, we'd end up
- * with stale nodes.
- */
- n = tdnode;
- /*
- * TMPFS_LOCK guaranties that no nodes are freed while
- * traversing the list. Nodes can only be marked as
- * removed: tn_parent == NULL.
- */
- TMPFS_LOCK(tmp);
- TMPFS_NODE_LOCK(n);
- while (n != n->tn_dir.tn_parent) {
- struct tmpfs_node *parent;
-
- if (n == fnode) {
- TMPFS_NODE_UNLOCK(n);
- TMPFS_UNLOCK(tmp);
- error = EINVAL;
- if (newname != NULL)
- free(newname, M_TMPFSNAME);
- goto out_locked;
- }
- parent = n->tn_dir.tn_parent;
- TMPFS_NODE_UNLOCK(n);
- if (parent == NULL) {
- n = NULL;
- break;
- }
- TMPFS_NODE_LOCK(parent);
- if (parent->tn_dir.tn_parent == NULL) {
- TMPFS_NODE_UNLOCK(parent);
- n = NULL;
- break;
- }
- n = parent;
- }
- TMPFS_UNLOCK(tmp);
- if (n == NULL) {
- error = EINVAL;
- if (newname != NULL)
- free(newname, M_TMPFSNAME);
- goto out_locked;
- }
- TMPFS_NODE_UNLOCK(n);
-
- /* Adjust the parent pointer. */
- TMPFS_VALIDATE_DIR(fnode);
- TMPFS_NODE_LOCK(de->td_node);
- de->td_node->tn_dir.tn_parent = tdnode;
- TMPFS_NODE_UNLOCK(de->td_node);
-
- /*
- * As a result of changing the target of the '..'
- * entry, the link count of the source and target
- * directories has to be adjusted.
- */
- TMPFS_NODE_LOCK(tdnode);
- TMPFS_ASSERT_LOCKED(tdnode);
- tdnode->tn_links++;
- TMPFS_NODE_UNLOCK(tdnode);
-
- TMPFS_NODE_LOCK(fdnode);
- TMPFS_ASSERT_LOCKED(fdnode);
- fdnode->tn_links--;
- TMPFS_NODE_UNLOCK(fdnode);
}
+ if (exchange && tnode->tn_type == VDIR) {
+ MPASS(newname == NULL);
+ error = tmpfs_rename_check_parent(tmp, tdnode, tvp,
+ tnode, tde, fdnode, fcnp->cn_cred);
+ if (error != 0)
+ goto out_locked;
+ }
+ if (fnode->tn_type == VDIR)
+ tmpfs_rename_set_parent(fdnode, fnode, de, tdnode);
+ if (exchange && tnode->tn_type == VDIR)
+ tmpfs_rename_set_parent(tdnode, tnode, tde, fdnode);
+ }
+ if (exchange) {
+ de->td_node = tnode;
+ tde->td_node = fnode;
+ if (tmpfs_use_nc(fvp)) {
+ cache_purge(fvp);
+ cache_purge(tvp);
+ cache_enter(tdvp, fvp, tcnp);
+ cache_enter(fdvp, tvp, fcnp);
+ }
+ fdnode->tn_status |= TMPFS_NODE_MODIFIED | TMPFS_NODE_CHANGED;
+ fdnode->tn_accessed = true;
+ tmpfs_update(fdvp);
+ if (fdvp != tdvp) {
+ tdnode->tn_status |= TMPFS_NODE_MODIFIED |
+ TMPFS_NODE_CHANGED;
+ tdnode->tn_accessed = true;
+ tmpfs_update(tdvp);
+ }
+ goto out_locked;
}
/*
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -3786,7 +3786,10 @@
int error;
short irflag;
- if ((flags & ~(AT_RENAME_NOREPLACE)) != 0)
+ if ((flags & ~(AT_RENAME_NOREPLACE | AT_RENAME_EXCHANGE)) != 0)
+ return (EINVAL);
+ if ((flags & (AT_RENAME_NOREPLACE | AT_RENAME_EXCHANGE)) ==
+ (AT_RENAME_NOREPLACE | AT_RENAME_EXCHANGE))
return (EINVAL);
again:
tmp = mp = NULL;
@@ -3799,7 +3802,8 @@
return (error);
} else {
#endif
- NDINIT_ATRIGHTS(&fromnd, DELETE, WANTPARENT | AUDITVNODE1,
+ NDINIT_ATRIGHTS(&fromnd, (flags & AT_RENAME_EXCHANGE) != 0 ? RENAME :
+ DELETE, WANTPARENT | AUDITVNODE1,
pathseg, old, oldfd, &cap_renameat_source_rights);
if ((error = namei(&fromnd)) != 0)
return (error);
@@ -3845,6 +3849,10 @@
error = EEXIST;
goto out;
}
+ if (tvp == NULL && (flags & AT_RENAME_EXCHANGE) != 0) {
+ error = ENOENT;
+ goto out;
+ }
error = vn_start_write(fvp, &mp, V_NOWAIT);
if (error != 0) {
again1:
@@ -3887,12 +3895,15 @@
goto out;
}
if (tvp != NULL) {
- if (fvp->v_type == VDIR && tvp->v_type != VDIR) {
- error = ENOTDIR;
- goto out;
- } else if (fvp->v_type != VDIR && tvp->v_type == VDIR) {
- error = EISDIR;
- goto out;
+ if ((flags & AT_RENAME_EXCHANGE) == 0) {
+ if (fvp->v_type == VDIR && tvp->v_type != VDIR) {
+ error = ENOTDIR;
+ goto out;
+ } else if (fvp->v_type != VDIR &&
+ tvp->v_type == VDIR) {
+ error = EISDIR;
+ goto out;
+ }
}
#ifdef CAPABILITIES
if (newfd != AT_FDCWD && (tond.ni_resflags & NIRES_ABS) == 0) {
diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h
--- a/sys/sys/fcntl.h
+++ b/sys/sys/fcntl.h
@@ -260,7 +260,9 @@
#define AT_EMPTY_PATH 0x4000 /* Operate on dirfd if path is empty */
#define AT_RENAME_NOREPLACE 0x0001 /* Fail rename if target exists */
+#define AT_RENAME_EXCHANGE 0x0002 /* Atomically exchange 'from' and 'to' */
#define RENAME_NOREPLACE AT_RENAME_NOREPLACE
+#define RENAME_EXCHANGE AT_RENAME_EXCHANGE
#endif /* __BSD_VISIBLE */
/*

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