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block: handle invalid lseek returns gracefully

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In commit 223a23c198787328ae75bc65d84edf5fde33c0b6, we implemented a
workaround in the gluster driver to handle invalid values returned for
SEEK_DATA or SEEK_HOLE.

In some instances, these same invalid values can be seen in the posix
file handler as well - for example, it has been reported on FUSE gluster
mounts.

Calling assert() for these invalid values is overly harsh; we can safely
return -EIO and allow this case to be treated as a "learned nothing"
case (e.g., D4 / H4, as commented in the code).

This patch does the same thing that 223a23c198787 did for gluster.c,
except in file-posix.c

Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Jeff Cody 2018-04-03 00:37:26 -04:00 committed by Kevin Wolf
parent 3e4d88eabf
commit a03083a017
1 changed files with 12 additions and 2 deletions
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14
block/file-posix.c
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@ -2114,7 +2114,12 @@ static int find_allocation(BlockDriverState *bs, off_t start,
if (offs < 0) {
return -errno; /* D3 or D4 */
}
assert(offs >= start);
if (offs < start) {
/* This is not a valid return by lseek(). We are safe to just return
* -EIO in this case, and we'll treat it like D4. */
return -EIO;
}
if (offs > start) {
/* D2: in hole, next data at offs */
@ -2146,7 +2151,12 @@ static int find_allocation(BlockDriverState *bs, off_t start,
if (offs < 0) {
return -errno; /* D1 and (H3 or H4) */
}
assert(offs >= start);
if (offs < start) {
/* This is not a valid return by lseek(). We are safe to just return
* -EIO in this case, and we'll treat it like H4. */
return -EIO;
}
if (offs > start) {
/*