One of our test team hit a reiserfs_panic while running fsstress tests on
2.6.19-rc1. The message looks like :
REISERFS: panic(device Null superblock):
reiserfs[5676]: assertion !(p->path_length != 1 ) failed at
fs/reiserfs/stree.c:397:reiserfs_check_path: path not properly relsed.
The backtrace looked :
kernel BUG in reiserfs_panic at fs/reiserfs/prints.c:361!
.reiserfs_check_path+0x58/0x74
.reiserfs_get_block+0x1444/0x1508
.__block_prepare_write+0x1c8/0x558
.block_prepare_write+0x34/0x64
.reiserfs_prepare_write+0x118/0x1d0
.generic_file_buffered_write+0x314/0x82c
.__generic_file_aio_write_nolock+0x350/0x3e0
.__generic_file_write_nolock+0x78/0xb0
.generic_file_write+0x60/0xf0
.reiserfs_file_write+0x198/0x2038
.vfs_write+0xd0/0x1b4
.sys_write+0x4c/0x8c
syscall_exit+0x0/0x4
Upon debugging I found that the restart_transaction was not releasing
the path if the th->refcount was > 1.
/*static*/
int restart_transaction(struct reiserfs_transaction_handle *th,
struct inode *inode, struct path *path)
{
[...]
/* we cannot restart while nested */
if (th->t_refcount > 1) { <<- Path is not released in this case!
return 0;
}
pathrelse(path); <<- Path released here.
[...]
This could happen in such a situation :
In reiserfs/inode.c: reiserfs_get_block() ::
if (repeat == NO_DISK_SPACE || repeat == QUOTA_EXCEEDED) {
/* restart the transaction to give the journal a chance to free
** some blocks. releases the path, so we have to go back to
** research if we succeed on the second try
*/
SB_JOURNAL(inode->i_sb)->j_next_async_flush = 1;
-->> retval = restart_transaction(th, inode, &path); <<--
We are supposed to release the path, no matter we succeed or fail. But
if the th->refcount is > 1, the path is still valid. And,
if (retval)
goto failure;
repeat =
_allocate_block(th, block, inode,
&allocated_block_nr, NULL, create);
If the above allocate_block fails with NO_DISK_SPACE or QUOTA_EXCEEDED,
we would have path which is not released.
if (repeat != NO_DISK_SPACE && repeat != QUOTA_EXCEEDED) {
goto research;
}
if (repeat == QUOTA_EXCEEDED)
retval = -EDQUOT;
else
retval = -ENOSPC;
goto failure;
[...]
failure:
[...]
reiserfs_check_path(&path); << Panics here !
Attached here is a patch which could fix the issue.
fix reiserfs/inode.c : restart_transaction() to release the path in all
cases.
The restart_transaction() doesn't release the path when the the journal
handle has a refcount > 1. This would trigger a reiserfs_panic() if we
encounter an -ENOSPC / -EDQUOT in reiserfs_get_block().
Signed-off-by: Suzuki K P <suzuki@in.ibm.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: <reiserfs-dev@namesys.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
87b4126f10