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[Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure |
Date: |
Thu, 13 Nov 2014 11:17:02 +0100 |
When SEEK_HOLE tells us we're in a hole, we try SEEK_DATA to find its
end. When that fails, we pretend the hole extends to the end of file.
Wrong. Except when SEEK_END fails, we screw up and claim it extends
to offset -1. More wrong.
Fortunately, these seeks are very unlikely to fail. Fix it anyway, by
returning failure. The caller will then pretend there are no holes.
Inaccurate, but safe.
Signed-off-by: Markus Armbruster <address@hidden>
---
block/raw-posix.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index fd80d84..2a12a50 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1494,8 +1494,9 @@ static int try_seek_hole(BlockDriverState *bs, off_t
start, off_t *data,
} else {
/* On a hole. We need another syscall to find its end. */
*data = lseek(s->fd, start, SEEK_DATA);
- if (*data == -1) {
- *data = lseek(s->fd, 0, SEEK_END);
+ if (*data < 0) {
+ /* no idea where the hole ends, give up (unlikely to happen) */
+ return -errno;
}
}
--
1.9.3
- [Qemu-devel] [PATCH v2 0/4] raw-posix: Get rid of FIEMAP, and more, Markus Armbruster, 2014/11/13
- [Qemu-devel] [PATCH v2 2/4] raw-posix: SEEK_HOLE suffices, get rid of FIEMAP, Markus Armbruster, 2014/11/13
- [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure,
Markus Armbruster <=
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Max Reitz, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Kevin Wolf, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Eric Blake, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Eric Blake, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Max Reitz, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Eric Blake, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Eric Blake, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Eric Blake, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Eric Blake, 2014/11/13
- Re: [Qemu-devel] [PATCH v2 3/4] raw-posix: Fix try_seek_hole()'s handling of SEEK_DATA failure, Markus Armbruster, 2014/11/14