Eric Sandeen wrote:
David Chatterton wrote:
I assume the loop is further up the chain since kmem_alloc should
return NULL
when asked to alloc 0. So then the problem also lies further up the
chain in
checking for a 0 length before calling down, and/or not assuming we
are out of
memory when xfs_buf_get_noaddr fails.
Well, I set kdb breakpoints, and we only entered xfs_buf_get_noaddr
once, so I assume it's looping inside. But I was looking for bugs on,
um, another filesystem at the time, so didn't investigate much.
I can put it on my list of spare-time bugs to look at, or just thought
you guys may be interested as well.
<spare-time>
well, as a quick fix, this seems to do the trick:
--- linux-2.6.18.orig/fs/xfs/xfs_log_recover.c
+++ linux-2.6.18/fs/xfs/xfs_log_recover.c
@@ -75,6 +75,9 @@ xlog_get_bp(
int num_bblks)
{
ASSERT(num_bblks > 0);
+ if (num_bblks <= 0) {
+ return NULL;
+ }
if (log->l_sectbb_log) {
if (num_bblks > 1)
but it's not the most helpful output:
XFS: Log inconsistent (didn't find previous header)
XFS: empty log check failed
XFS: log mount/recovery failed: error 5
XFS: log mount failed
... but not that bad I guess.
it's getting the 0 allocation because last & start are equal here:
num_blks 0 last 2756 start 2756
[<dec87bd5>] xlog_find_verify_log_record+0x45/0x2f2 [xfs]
[<dec88254>] xlog_find_tail+0x20e/0xb8d [xfs]
[<dec88be9>] xlog_recover+0x16/0x22d [xfs]
[<dec84338>] xfs_log_mount+0x4e4/0x530 [xfs]
[<dec8b2af>] xfs_mountfs+0xa58/0xf61 [xfs]
[<dec7dd7b>] xfs_ioinit+0x1e/0x23 [xfs]
[<dec91db8>] xfs_mount+0x7a8/0x875 [xfs]
[<deca2713>] vfs_mount+0x17/0x1a [xfs]
[<deca25b5>] xfs_fs_fill_super+0x6c/0x1b3 [xfs]
[<c047bd7b>] get_sb_bdev+0xd1/0x11f
[<deca1ac9>] xfs_fs_get_sb+0x20/0x25 [xfs]
[<c047b933>] vfs_kern_mount+0x83/0xf6
[<c047b9e8>] do_kern_mount+0x2d/0x3e
[<c048ee67>] do_mount+0x5fe/0x671
[<c048ef51>] sys_mount+0x77/0xae
[<c0403fb3>] syscall_call+0x7/0xb
and they're equal because in xlog_find_zeroed():
start_blk = last_blk - num_scan_bblks;
/* here, start 2756 last 3268 num_scan_bblks 512 */
/*
* We search for any instances of cycle number 0 that occur before
* our current estimate of the head. What we're trying to detect is
* 1 ... | 0 | 1 | 0...
* ^ binary search ends here
*/
if ((error = xlog_find_verify_cycle(log, start_blk,
(int)num_scan_bblks, 0, &new_blk)))
goto bp_err;
if (new_blk != -1)
last_blk = new_blk;
/* now new last_blk == new_blk == 2756, same as start */
/*
* Potentially backup over partial log record write. We don't need
* to search the end of the log because we know it is zero.
*/
if ((error = xlog_find_verify_log_record(log, start_blk,
&last_blk, 0)) == -1) {
Maybe that's enough for Tim to come up with a better check :)
-Eric
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