Messages in this thread Patch in this message | | | Date | Tue, 17 Oct 2006 18:12:19 -0700 | From | Suzuki K P <> | Subject | [RFC] Patch to fix reiserfs bad path release panic on 2.6.19-rc1 |
| |
hi,
One of our test team hit a reiserfs_panic while running fsstress tests on 2.6.19-rc1. The message looks like :
<0>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! 3:mon> t [c0000000688aafb0] c00000000014f964 .reiserfs_check_path+0x58/0x74 [c0000000688ab030] c000000000135474 .reiserfs_get_block+0x1444/0x1508 [c0000000688ab2a0] c0000000000cdc8c .__block_prepare_write+0x1c8/0x558 [c0000000688ab3d0] c0000000000ce050 .block_prepare_write+0x34/0x64 [c0000000688ab450] c000000000132784 .reiserfs_prepare_write+0x118/0x1d0 [c0000000688ab500] c00000000009df14 .generic_file_buffered_write+0x314/0x82c [c0000000688ab6b0] c00000000009e77c .__generic_file_aio_write_nolock+0x350/0x3e0 [c0000000688ab7e0] c00000000009e988 .__generic_file_write_nolock+0x78/0xb0 [c0000000688ab950] c00000000009eb18 .generic_file_write+0x60/0xf0 [c0000000688aba10] c000000000138d2c .reiserfs_file_write+0x198/0x2038 [c0000000688abcf0] c0000000000ca1a8 .vfs_write+0xd0/0x1b4 [c0000000688abd90] c0000000000ca8c8 .sys_write+0x4c/0x8c [c0000000688abe30] c00000000000871c 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.
Comments ?
Thanks,
Suzuki K P Linux Technology Center, IBM Systems & Technology Labs. * 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>
Index: linux-2.6.19-rc1/fs/reiserfs/inode.c =================================================================== --- linux-2.6.19-rc1.orig/fs/reiserfs/inode.c 2006-10-12 02:13:12.000000000 -0700 +++ linux-2.6.19-rc1/fs/reiserfs/inode.c 2006-10-13 16:38:32.000000000 -0700 @@ -216,11 +216,12 @@ BUG_ON(!th->t_trans_id); BUG_ON(!th->t_refcount); + pathrelse(path); + /* we cannot restart while nested */ if (th->t_refcount > 1) { return 0; } - pathrelse(path); reiserfs_update_sd(th, inode); err = journal_end(th, s, len); if (!err) {
| |