linux/fs/ext4, branch v3.0.9

ext4: remove i_mutex lock in ext4_evict_inode to fix lockdep complaining

2011-11-11T17:37:16Z

commit 8c0bec2151a47906bf779c6715a10ce04453ab77 upstream. The i_mutex lock and flush_completed_IO() added by commit 2581fdc810 in ext4_evict_inode() causes lockdep complaining about potential deadlock in several places. In most/all of these LOCKDEP complaints it looks like it's a false positive, since many of the potential circular locking cases can't take place by the time the ext4_evict_inode() is called; but since at the very least it may mask real problems, we need to address this. This change removes the flush_completed_IO() and i_mutex lock in ext4_evict_inode(). Instead, we take a different approach to resolve the software lockup that commit 2581fdc810 intends to fix. Rather than having ext4-dio-unwritten thread wait for grabing the i_mutex lock of an inode, we use mutex_trylock() instead, and simply requeue the work item if we fail to grab the inode's i_mutex lock. This should speed up work queue processing in general and also prevents the following deadlock scenario: During page fault, shrink_icache_memory is called that in turn evicts another inode B. Inode B has some pending io_end work so it calls ext4_ioend_wait() that waits for inode B's i_ioend_count to become zero. However, inode B's ioend work was queued behind some of inode A's ioend work on the same cpu's ext4-dio-unwritten workqueue. As the ext4-dio-unwritten thread on that cpu is processing inode A's ioend work, it tries to grab inode A's i_mutex lock. Since the i_mutex lock of inode A is still hold before the page fault happened, we enter a deadlock. Signed-off-by: Jiaying Zhang Signed-off-by: "Theodore Ts'o" Cc: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

ext4: fix race in xattr block allocation path

2011-11-11T17:36:34Z

commit 6d6a435190bdf2e04c9465cde5bdc3ac68cf11a4 upstream. Ceph users reported that when using Ceph on ext4, the filesystem would often become corrupted, containing inodes with incorrect i_blocks counters. I managed to reproduce this with a very hacked-up "streamtest" binary from the Ceph tree. Ceph is doing a lot of xattr writes, to out-of-inode blocks. There is also another thread which does sync_file_range and close, of the same files. The problem appears to happen due to this race: sync/flush thread xattr-set thread ----------------- ---------------- do_writepages ext4_xattr_set ext4_da_writepages ext4_xattr_set_handle mpage_da_map_blocks ext4_xattr_block_set set DELALLOC_RESERVE ext4_new_meta_blocks ext4_mb_new_blocks if (!i_delalloc_reserved_flag) vfs_dq_alloc_block ext4_get_blocks down_write(i_data_sem) set i_delalloc_reserved_flag ... up_write(i_data_sem) if (i_delalloc_reserved_flag) vfs_dq_alloc_block_nofail In other words, the sync/flush thread pops in and sets i_delalloc_reserved_flag on the inode, which makes the xattr thread think that it's in a delalloc path in ext4_new_meta_blocks(), and add the block for a second time, after already having added it once in the !i_delalloc_reserved_flag case in ext4_mb_new_blocks The real problem is that we shouldn't be using the DELALLOC_RESERVED state flag, and instead we should be passing EXT4_GET_BLOCKS_DELALLOC_RESERVE down to ext4_map_blocks() instead of using an inode state flag. We'll fix this for now with using i_data_sem to prevent this race, but this is really not the right way to fix things. Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

ext4: call ext4_handle_dirty_metadata with correct inode in ext4_dx_add_entry

2011-11-11T17:36:34Z

commit 5930ea643805feb50a2f8383ae12eb6f10935e49 upstream. ext4_dx_add_entry manipulates bh2 and frames[0].bh, which are two buffer_heads that point to directory blocks assigned to the directory inode. However, the function calls ext4_handle_dirty_metadata with the inode of the file that's being added to the directory, not the directory inode itself. Therefore, correct the code to dirty the directory buffers with the directory inode, not the file inode. Signed-off-by: Darrick J. Wong Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

ext4: ext4_mkdir should dirty dir_block with newly created directory inode

2011-11-11T17:36:34Z

commit f9287c1f2d329f4d78a3bbc9cf0db0ebae6f146a upstream. ext4_mkdir calls ext4_handle_dirty_metadata with dir_block and the inode "dir". Unfortunately, dir_block belongs to the newly created directory (which is "inode"), not the parent directory (which is "dir"). Fix the incorrect association. Signed-off-by: Darrick J. Wong Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

ext4: ext4_rename should dirty dir_bh with the correct directory

2011-11-11T17:36:33Z

commit bcaa992975041e40449be8c010c26192b8c8b409 upstream. When ext4_rename performs a directory rename (move), dir_bh is a buffer that is modified to update the '..' link in the directory being moved (old_inode). However, ext4_handle_dirty_metadata is called with the old parent directory inode (old_dir) and dir_bh, which is incorrect because dir_bh does not belong to the parent inode. Fix this error. Signed-off-by: Darrick J. Wong Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

ext2,ext3,ext4: don't inherit APPEND_FL or IMMUTABLE_FL for new inodes

2011-11-11T17:36:32Z

commit 1cd9f0976aa4606db8d6e3dc3edd0aca8019372a upstream. This doesn't make much sense, and it exposes a bug in the kernel where attempts to create a new file in an append-only directory using O_CREAT will fail (but still leave a zero-length file). This was discovered when xfstests #79 was generalized so it could run on all file systems. Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage

2011-10-03T18:40:43Z

commit 6e6938b6d3130305a5960c86b1a9b21e58cf6144 upstream. sync(2) is performed in two stages: the WB_SYNC_NONE sync and the WB_SYNC_ALL sync. Identify the first stage with .tagged_writepages and do livelock prevention for it, too. Jan's commit f446daaea9 ("mm: implement writeback livelock avoidance using page tagging") is a partial fix in that it only fixed the WB_SYNC_ALL phase livelock. Although ext4 is tested to no longer livelock with commit f446daaea9, it may due to some "redirty_tail() after pages_skipped" effect which is by no means a guarantee for _all_ the file systems. Note that writeback_inodes_sb() is called by not only sync(), they are treated the same because the other callers also need livelock prevention. Impact: It changes the order in which pages/inodes are synced to disk. Now in the WB_SYNC_NONE stage, it won't proceed to write the next inode until finished with the current inode. Acked-by: Jan Kara CC: Dave Chinner Signed-off-by: Wu Fengguang Signed-off-by: Greg Kroah-Hartman

ext4: fix nomblk_io_submit option so it correctly converts uninit blocks

2011-08-29T20:29:11Z

commit 9dd75f1f1a02d656a11a7b9b9e6c2759b9c1e946 upstream. Bug discovered by Jan Kara: Finally, commit 1449032be17abb69116dbc393f67ceb8bd034f92 returned back the old IO submission code but apparently it forgot to return the old handling of uninitialized buffers so we unconditionnaly call block_write_full_page() without specifying end_io function. So AFAICS we never convert unwritten extents to written in some cases. For example when I mount the fs as: mount -t ext4 -o nomblk_io_submit,dioread_nolock /dev/ubdb /mnt and do int fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0600); char buf[1024]; memset(buf, 'a', sizeof(buf)); fallocate(fd, 0, 0, 16384); write(fd, buf, sizeof(buf)); I get a file full of zeros (after remounting the filesystem so that pagecache is dropped) instead of seeing the first KB contain 'a's. Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.

2011-08-29T20:29:11Z

commit 32c80b32c053dc52712dedac5e4d0aa7c93fc353 upstream. EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten should be done simultaneously since ext4_end_io_nolock always clear the flag and decrease the counter in the same time. We don't increase i_aiodio_unwritten when setting EXT4_IO_END_UNWRITTEN so it will go nagative and causes some process to wait forever. Part of the patch came from Eric in his e-mail, but it doesn't fix the problem met by Michael actually. http://marc.info/?l=linux-ext4&m=131316851417460&w=2 Reported-and-Tested-by: Michael Tokarev Signed-off-by: Eric Sandeen Signed-off-by: Tao Ma Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

ext4: call ext4_ioend_wait and ext4_flush_completed_IO in ext4_evict_inode

2011-08-29T20:29:10Z

commit 2581fdc810889fdea97689cb62481201d579c796 upstream. Flush inode's i_completed_io_list before calling ext4_io_wait to prevent the following deadlock scenario: A page fault happens while some process is writing inode A. During page fault, shrink_icache_memory is called that in turn evicts another inode B. Inode B has some pending io_end work so it calls ext4_ioend_wait() that waits for inode B's i_ioend_count to become zero. However, inode B's ioend work was queued behind some of inode A's ioend work on the same cpu's ext4-dio-unwritten workqueue. As the ext4-dio-unwritten thread on that cpu is processing inode A's ioend work, it tries to grab inode A's i_mutex lock. Since the i_mutex lock of inode A is still hold before the page fault happened, we enter a deadlock. Also moves ext4_flush_completed_IO and ext4_ioend_wait from ext4_destroy_inode() to ext4_evict_inode(). During inode deleteion, ext4_evict_inode() is called before ext4_destroy_inode() and in ext4_evict_inode(), we may call ext4_truncate() without holding i_mutex lock. As a result, there is a race between flush_completed_IO that is called from ext4_ext_truncate() and ext4_end_io_work, which may cause corruption on an io_end structure. This change moves ext4_flush_completed_IO and ext4_ioend_wait from ext4_destroy_inode() to ext4_evict_inode() to resolve the race between ext4_truncate() and ext4_end_io_work during inode deletion. Signed-off-by: Jiaying Zhang Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman