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Differential D19140 Diff 54003 head/stand/libsa/zfs/zfs.c

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head/stand/libsa/zfs/zfs.c

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return (0); return (0);
} }
} }
static int static int
vdev_read(vdev_t *vdev, void *priv, off_t offset, void *buf, size_t bytes) vdev_read(vdev_t *vdev, void *priv, off_t offset, void *buf, size_t bytes)
{ {
int fd, ret; int fd, ret;
size_t res, size, remainder, rb_size, blksz; size_t res, head, tail, total_size, full_sec_size;
unsigned secsz; unsigned secsz, do_tail_read;
off_t off; off_t start_sec;
char *bouncebuf, *rb_buf; char *outbuf, *bouncebuf;
fd = (uintptr_t) priv; fd = (uintptr_t) priv;
outbuf = (char *) buf;
bouncebuf = NULL; bouncebuf = NULL;
ret = ioctl(fd, DIOCGSECTORSIZE, &secsz); ret = ioctl(fd, DIOCGSECTORSIZE, &secsz);
if (ret != 0) if (ret != 0)
return (ret); return (ret);
off = offset / secsz; /*
remainder = offset % secsz; * Handling reads of arbitrary offset and size - multi-sector case
if (lseek(fd, off * secsz, SEEK_SET) == -1) * and single-sector case.
return (errno); *
* Multi-sector Case
* (do_tail_read = true if tail > 0)
*
* |<----------------------total_size--------------------->|
* | |
* |<--head-->|<--------------bytes------------>|<--tail-->|
* | | | |
* | | |<~full_sec_size~>| | |
* +------------------+ +------------------+
* | |0101010| . . . |0101011| |
* +------------------+ +------------------+
* start_sec start_sec + n
*
*
* Single-sector Case
* (do_tail_read = false)
*
* |<------total_size = secsz----->|
* | |
* |<-head->|<---bytes--->|<-tail->|
* +-------------------------------+
* | |0101010101010| |
* +-------------------------------+
* start_sec
*/
start_sec = offset / secsz;
head = offset % secsz;
total_size = roundup2(head + bytes, secsz);
tail = total_size - (head + bytes);
do_tail_read = ((tail > 0) && (head + bytes > secsz));
full_sec_size = total_size;
if (head > 0)
full_sec_size -= secsz;
if (do_tail_read)
full_sec_size -= secsz;
rb_buf = buf; /* Return of partial sector data requires a bounce buffer. */
rb_size = bytes; if ((head > 0) || do_tail_read) {
size = roundup2(bytes + remainder, secsz);
blksz = size;
if (remainder != 0 || size != bytes) {
bouncebuf = zfs_alloc(secsz); bouncebuf = zfs_alloc(secsz);
if (bouncebuf == NULL) { if (bouncebuf == NULL) {
printf("vdev_read: out of memory\n"); printf("vdev_read: out of memory\n");
return (ENOMEM); return (ENOMEM);
} }
rb_buf = bouncebuf;
blksz = rb_size - remainder;
} }
while (bytes > 0) { if (lseek(fd, start_sec * secsz, SEEK_SET) == -1)
res = read(fd, rb_buf, rb_size); return (errno);
if (res != rb_size) {
/* Partial data return from first sector */
if (head > 0) {
res = read(fd, bouncebuf, secsz);
if (res != secsz) {
ret = EIO; ret = EIO;
goto error; goto error;
} }
if (bytes < blksz) memcpy(outbuf, bouncebuf + head, secsz - head);
blksz = bytes; outbuf += secsz - head;
if (bouncebuf != NULL) }
memcpy(buf, rb_buf + remainder, blksz);
buf = (void *)((uintptr_t)buf + blksz); /* Full data return from read sectors */
bytes -= blksz; if (full_sec_size > 0) {
remainder = 0; res = read(fd, outbuf, full_sec_size);
blksz = rb_size; if (res != full_sec_size) {
ret = EIO;
goto error;
}
outbuf += full_sec_size;
}
/* Partial data return from last sector */
if (do_tail_read) {
res = read(fd, bouncebuf, secsz);
if (res != secsz) {
ret = EIO;
goto error;
}
memcpy(outbuf, bouncebuf, secsz - tail);
} }
ret = 0; ret = 0;
error: error:
if (bouncebuf != NULL) if (bouncebuf != NULL)
zfs_free(bouncebuf, secsz); zfs_free(bouncebuf, secsz);
return (ret); return (ret);
} }
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