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由 Suzuki K P 提交于
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: NSuzuki 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: NJan Kara <jack@suse.cz> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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