108 lines
3.7 KiB
Diff
108 lines
3.7 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
From: Jeff Cody <jcody@redhat.com>
|
|
Date: Tue, 23 May 2017 13:27:50 -0400
|
|
Subject: [PATCH] block/gluster: glfs_lseek() workaround
|
|
|
|
On current released versions of glusterfs, glfs_lseek() will sometimes
|
|
return invalid values for SEEK_DATA or SEEK_HOLE. For SEEK_DATA and
|
|
SEEK_HOLE, the returned value should be >= the passed offset, or < 0 in
|
|
the case of error:
|
|
|
|
LSEEK(2):
|
|
|
|
off_t lseek(int fd, off_t offset, int whence);
|
|
|
|
[...]
|
|
|
|
SEEK_HOLE
|
|
Adjust the file offset to the next hole in the file greater
|
|
than or equal to offset. If offset points into the middle of
|
|
a hole, then the file offset is set to offset. If there is no
|
|
hole past offset, then the file offset is adjusted to the end
|
|
of the file (i.e., there is an implicit hole at the end of
|
|
any file).
|
|
|
|
[...]
|
|
|
|
RETURN VALUE
|
|
Upon successful completion, lseek() returns the resulting
|
|
offset location as measured in bytes from the beginning of the
|
|
file. On error, the value (off_t) -1 is returned and errno is
|
|
set to indicate the error
|
|
|
|
However, occasionally glfs_lseek() for SEEK_HOLE/DATA will return a
|
|
value less than the passed offset, yet greater than zero.
|
|
|
|
For instance, here are example values observed from this call:
|
|
|
|
offs = glfs_lseek(s->fd, start, SEEK_HOLE);
|
|
if (offs < 0) {
|
|
return -errno; /* D1 and (H3 or H4) */
|
|
}
|
|
|
|
start == 7608336384
|
|
offs == 7607877632
|
|
|
|
This causes QEMU to abort on the assert test. When this value is
|
|
returned, errno is also 0.
|
|
|
|
This is a reported and known bug to glusterfs:
|
|
https://bugzilla.redhat.com/show_bug.cgi?id=1425293
|
|
|
|
Although this is being fixed in gluster, we still should work around it
|
|
in QEMU, given that multiple released versions of gluster behave this
|
|
way.
|
|
|
|
This patch treats the return case of (offs < start) the same as if an
|
|
error value other than ENXIO is returned; we will assume we learned
|
|
nothing, and there are no holes in the file.
|
|
|
|
Signed-off-by: Jeff Cody <jcody@redhat.com>
|
|
Reviewed-by: Eric Blake <eblake@redhat.com>
|
|
Reviewed-by: Niels de Vos <ndevos@redhat.com>
|
|
Message-id: 87c0140e9407c08f6e74b04131b610f2e27c014c.1495560397.git.jcody@redhat.com
|
|
Signed-off-by: Jeff Cody <jcody@redhat.com>
|
|
---
|
|
block/gluster.c | 18 ++++++++++++++++--
|
|
1 file changed, 16 insertions(+), 2 deletions(-)
|
|
|
|
diff --git a/block/gluster.c b/block/gluster.c
|
|
index 4fdf68f1fc..06421ef79d 100644
|
|
--- a/block/gluster.c
|
|
+++ b/block/gluster.c
|
|
@@ -1287,7 +1287,14 @@ 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. Unfortunately some
|
|
+ * versions of gluster server will return offs < start, so an assert
|
|
+ * here will unnecessarily abort QEMU. */
|
|
+ return -EIO;
|
|
+ }
|
|
|
|
if (offs > start) {
|
|
/* D2: in hole, next data at offs */
|
|
@@ -1319,7 +1326,14 @@ 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. Unfortunately some
|
|
+ * versions of gluster server will return offs < start, so an assert
|
|
+ * here will unnecessarily abort QEMU. */
|
|
+ return -EIO;
|
|
+ }
|
|
|
|
if (offs > start) {
|
|
/*
|
|
--
|
|
2.11.0
|
|
|