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* Revert "ext4: don't release page refs in ext4_end_bio()"Linus Torvalds2012-03-291-4/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit b43d17f319f2c502b17139d1cf70731b2b62c644. Dave Jones reports that it causes lockups on his laptop, and his debug output showed a lot of processes hung waiting for page_writeback (or more commonly - processes hung waiting for a lock that was held during that writeback wait). The page_writeback hint made Ted suggest that Dave look at this commit, and Dave verified that reverting it makes his problems go away. Ted says: "That commit fixes a race which is seen when you write into fallocated (and hence uninitialized) disk blocks under *very* heavy memory pressure. Furthermore, although theoretically it could trigger under normal direct I/O writes, it only seems to trigger if you are issuing a huge number of AIO writes, such that a just-written page can get evicted from memory, and then read back into memory, before the workqueue has a chance to update the extent tree. This race has been around for a little over a year, and no one noticed until two months ago; it only happens under fairly exotic conditions, and in fact even after trying very hard to create a simple repro under lab conditions, we could only reproduce the problem and confirm the fix on production servers running MySQL on very fast PCIe-attached flash devices. Given that Dave was able to hit this problem pretty quickly, if we confirm that this commit is at fault, the only reasonable thing to do is to revert it IMO." Reported-and-tested-by: Dave Jones <davej@redhat.com> Acked-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ext4: don't release page refs in ext4_end_bio()Curt Wohlgemuth2012-03-051-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | We can clear PageWriteback on each page when the IO completes, but we can't release the references on the page until we convert any uninitialized extents. Without this patch, the use of the dioread_nolock mount option can break buffered writes, because extents may not be converted by the time a subsequent buffered read comes in; if the page is not in the page cache, a read will return zeros if the extent is still uninitialized. I tested this with a (temporary) patch that adds a call to msleep(1000) at the start of ext4_end_io_work(), to delay processing of each DIO-unwritten work queue item. With this msleep(), a simple workload of fallocate write fadvise read will fail without this patch, succeeds with it. Signed-off-by: Curt Wohlgemuth <curtw@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix race between sync and completed io workJeff Moyer2012-03-051-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following command line will leave the aio-stress process unkillable on an ext4 file system (in my case, mounted on /mnt/test): aio-stress -t 20 -s 10 -O -S -o 2 -I 1000 /mnt/test/aiostress.3561.4 /mnt/test/aiostress.3561.4.20 /mnt/test/aiostress.3561.4.19 /mnt/test/aiostress.3561.4.18 /mnt/test/aiostress.3561.4.17 /mnt/test/aiostress.3561.4.16 /mnt/test/aiostress.3561.4.15 /mnt/test/aiostress.3561.4.14 /mnt/test/aiostress.3561.4.13 /mnt/test/aiostress.3561.4.12 /mnt/test/aiostress.3561.4.11 /mnt/test/aiostress.3561.4.10 /mnt/test/aiostress.3561.4.9 /mnt/test/aiostress.3561.4.8 /mnt/test/aiostress.3561.4.7 /mnt/test/aiostress.3561.4.6 /mnt/test/aiostress.3561.4.5 /mnt/test/aiostress.3561.4.4 /mnt/test/aiostress.3561.4.3 /mnt/test/aiostress.3561.4.2 This is using the aio-stress program from the xfstests test suite. That particular command line tells aio-stress to do random writes to 20 files from 20 threads (one thread per file). The files are NOT preallocated, so you will get writes to random offsets within the file, thus creating holes and extending i_size. It also opens the file with O_DIRECT and O_SYNC. On to the problem. When an I/O requires unwritten extent conversion, it is queued onto the completed_io_list for the ext4 inode. Two code paths will pull work items from this list. The first is the ext4_end_io_work routine, and the second is ext4_flush_completed_IO, which is called via the fsync path (and O_SYNC handling, as well). There are two issues I've found in these code paths. First, if the fsync path beats the work routine to a particular I/O, the work routine will free the io_end structure! It does not take into account the fact that the io_end may still be in use by the fsync path. I've fixed this issue by adding yet another IO_END flag, indicating that the io_end is being processed by the fsync path. The second problem is that the work routine will make an assignment to io->flag outside of the lock. I have witnessed this result in a hang at umount. Moving the flag setting inside the lock resolved that problem. The problem was introduced by commit b82e384c7b ("ext4: optimize locking for end_io extent conversion"), which first appeared in 3.2. As such, the fix should be backported to that release (probably along with the unwritten extent conversion race fix). Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> CC: stable@kernel.org
* ext4: fix race between unwritten extent conversion and truncateJeff Moyer2012-02-201-0/+2
| | | | | | | | | | | | | | | | | | | | | | The following comment in ext4_end_io_dio caught my attention: /* XXX: probably should move into the real I/O completion handler */ inode_dio_done(inode); The truncate code takes i_mutex, then calls inode_dio_wait. Because the ext4 code path above will end up dropping the mutex before it is reacquired by the worker thread that does the extent conversion, it seems to me that the truncate can happen out of order. Jan Kara mentioned that this might result in error messages in the system logs, but that should be the extent of the "damage." The fix is pretty straight-forward: don't call inode_dio_done until the extent conversion is complete. Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@vger.kernel.org
* Merge branch 'for_linus' of ↵Linus Torvalds2012-01-091-1/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs * 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: ext2/3/4: delete unneeded includes of module.h ext{3,4}: Fix potential race when setversion ioctl updates inode udf: Mark LVID buffer as uptodate before marking it dirty ext3: Don't warn from writepage when readonly inode is spotted after error jbd: Remove j_barrier mutex reiserfs: Force inode evictions before umount to avoid crash reiserfs: Fix quota mount option parsing udf: Treat symlink component of type 2 as / udf: Fix deadlock when converting file from in-ICB one to normal one udf: Cleanup calling convention of inode_getblk() ext2: Fix error handling on inode bitmap corruption ext3: Fix error handling on inode bitmap corruption ext3: replace ll_rw_block with other functions ext3: NULL dereference in ext3_evict_inode() jbd: clear revoked flag on buffers before a new transaction started ext3: call ext3_mark_recovery_complete() when recovery is really needed
| * ext2/3/4: delete unneeded includes of module.hPaul Gortmaker2012-01-091-1/+0
| | | | | | | | | | | | | | | | | | | | | | Delete any instances of include module.h that were not strictly required. In the case of ext2, the declaration of MODULE_LICENSE etc. were in inode.c but the module_init/exit were in super.c, so relocate the MODULE_LICENCE/AUTHOR block to super.c which makes it consistent with ext3 and ext4 at the same time. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Jan Kara <jack@suse.cz>
* | ext4: handle EOF correctly in ext4_bio_write_page()Yongqiang Yang2011-12-131-0/+12
|/ | | | | | | | | We need to zero out part of a page which beyond EOF before setting uptodate, otherwise, mapread or write will see non-zero data beyond EOF. Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
* ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwrittenTao Ma2011-10-311-4/+2
| | | | | | | | | | | | | | | 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 have found some bugs that the flag is set while leaving i_aiodio_unwritten unchanged(commit 32c80b32c053d). So this patch just tries to create a helper function to wrap them to avoid any future bug. The idea is inspired by Eric. Cc: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: optimize locking for end_io extent conversionTheodore Ts'o2011-10-311-26/+11
| | | | | | | | | | | | | | | | | Now that we are doing the locking correctly, we need to grab the i_completed_io_lock() twice per end_io. We can clean this up by removing the structure from the i_complted_io_list, and use this as the locking mechanism to prevent ext4_flush_completed_IO() racing against ext4_end_io_work(), instead of clearing the EXT4_IO_END_UNWRITTEN in io->flag. In addition, if the ext4_convert_unwritten_extents() returns an error, we no longer keep the end_io structure on the linked list. This doesn't help, because it tends to lock up the file system and wedges the system. That's one way to call attention to the problem, but it doesn't help the overall robustness of the system. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove unnecessary call to waitqueue_active()Theodore Ts'o2011-10-301-11/+4
| | | | | | | The usage of waitqueue_active() is not necessary, and introduces (I believe) a hard-to-hit race. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Use correct locking for ext4_end_io_nolock()Tao Ma2011-10-301-3/+11
| | | | | | | | | | | | | We must hold i_completed_io_lock when manipulating anything on the i_completed_io_list linked list. This includes io->lock, which we were checking in ext4_end_io_nolock(). So move this check to ext4_end_io_work(). This also has the bonus of avoiding extra work if it is already done without needing to take the mutex. Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove i_mutex lock in ext4_evict_inode to fix lockdep complainingJiaying Zhang2011-08-311-1/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <jiayingz@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.Tao Ma2011-08-131-2/+4
| | | | | | | | | | | | | | | | | | | | | 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<mjt@tls.msk.ru> Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
* ext4: remove loop around bio_alloc()Theodore Ts'o2011-06-291-5/+1
| | | | | | | | These days, bio_alloc() is guaranteed to never fail (as long as nvecs is less than BIO_MAX_PAGES), so we don't need the loop around the struct bio allocation. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: don't set PageUptodate in ext4_end_bio()Curt Wohlgemuth2011-04-301-28/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the bio completion routine, we should not be setting PageUptodate at all -- it's set at sys_write() time, and is unaffected by success/failure of the write to disk. This can cause a page corruption bug when the file system's block size is less than the architecture's VM page size. if we have only written a single block -- we might end up setting the page's PageUptodate flag, indicating that page is completely read into memory, which may not be true. This could cause subsequent reads to get bad data. This commit also takes the opportunity to clean up error handling in ext4_end_bio(), and remove some extraneous code: - fixes ext4_end_bio() to set AS_EIO in the page->mapping->flags on error, which was left out by mistake. This is needed so that fsync() will return an error if there was an I/O error. - remove the clear_buffer_dirty() call on unmapped buffers for each page. - consolidate page/buffer error handling in a single section. Signed-off-by: Curt Wohlgemuth <curtw@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reported-by: Jim Meyering <jim@meyering.net> Reported-by: Hugh Dickins <hughd@google.com> Cc: Mingming Cao <cmm@us.ibm.com>
* Merge branch 'for_linus' of ↵Linus Torvalds2011-03-251-4/+9
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 * 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (43 commits) ext4: fix a BUG in mb_mark_used during trim. ext4: unused variables cleanup in fs/ext4/extents.c ext4: remove redundant set_buffer_mapped() in ext4_da_get_block_prep() ext4: add more tracepoints and use dev_t in the trace buffer ext4: don't kfree uninitialized s_group_info members ext4: add missing space in printk's in __ext4_grp_locked_error() ext4: add FITRIM to compat_ioctl. ext4: handle errors in ext4_clear_blocks() ext4: unify the ext4_handle_release_buffer() api ext4: handle errors in ext4_rename jbd2: add COW fields to struct jbd2_journal_handle jbd2: add the b_cow_tid field to journal_head struct ext4: Initialize fsync transaction ids in ext4_new_inode() ext4: Use single thread to perform DIO unwritten convertion ext4: optimize ext4_bio_write_page() when no extent conversion is needed ext4: skip orphan cleanup if fs has unknown ROCOMPAT features ext4: use the nblocks arg to ext4_truncate_restart_trans() ext4: fix missing iput of root inode for some mount error paths ext4: make FIEMAP and delayed allocation play well together ext4: suppress verbose debugging information if malloc-debug is off ... Fi up conflicts in fs/ext4/super.c due to workqueue changes
| * ext4: optimize ext4_bio_write_page() when no extent conversion is neededTheodore Ts'o2011-02-281-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | If no extent conversion is required, wake up any processes waiting for the page's writeback to be complete and free the ext4_io_end structure directly in ext4_end_bio() instead of dropping it on the linked list (which requires taking a spinlock to queue and dequeue the io_end structure), and waiting for the workqueue to do this work. This removes an extra scheduling delay before process waiting for an fsync() to complete gets woken up, and it also reduces the CPU overhead for a random write workload. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
| * ext4: don't leave PageWriteback set after memory failureTheodore Ts'o2011-02-271-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In ext4_bio_write_page(), if the memory allocation for the struct ext4_io_page fails, it returns with the page's PageWriteback flag set. This will end up causing the page not to skip writeback in WB_SYNC_NONE mode, and in WB_SYNC_ALL mode (i.e., on a sync, fsync, or umount) the writeback daemon will get stuck forever on the wait_on_page_writeback() function in write_cache_pages_da(). Or, if journalling is enabled and the file gets deleted, it the journal thread can get stuck in journal_finish_inode_data_buffers() call to filemap_fdatawait(). Another place where things can get hung up is in truncate_inode_pages(), called out of ext4_evict_inode(). Fix this by not setting PageWriteback until after we have successfully allocated the struct ext4_io_page. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
| * ext4: Fix sparse warning: Using plain integer as NULL pointerPeter Huewe2011-02-211-2/+2
| | | | | | | | | | | | | | | | This patch fixes the warning "Using plain integer as NULL pointer", generated by sparse, by replacing the offending 0s with NULL. Signed-off-by: Peter Huewe <peterhuewe@gmx.de> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* | block: kill off REQ_UNPLUGJens Axboe2011-03-101-2/+1
|/ | | | | | | | | | With the plugging now being explicitly controlled by the submitter, callers need not pass down unplugging hints to the block layer. If they want to unplug, it's because they manually plugged on their own - in which case, they should just unplug at will. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* ext4: serialize unaligned asynchronous DIOEric Sandeen2011-02-121-12/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ext4 has a data corruption case when doing non-block-aligned asynchronous direct IO into a sparse file, as demonstrated by xfstest 240. The root cause is that while ext4 preallocates space in the hole, mappings of that space still look "new" and dio_zero_block() will zero out the unwritten portions. When more than one AIO thread is going, they both find this "new" block and race to zero out their portion; this is uncoordinated and causes data corruption. Dave Chinner fixed this for xfs by simply serializing all unaligned asynchronous direct IO. I've done the same here. The difference is that we only wait on conversions, not all IO. This is a very big hammer, and I'm not very pleased with stuffing this into ext4_file_write(). But since ext4 is DIO_LOCKING, we need to serialize it at this high level. I tried to move this into ext4_ext_direct_IO, but by then we have the i_mutex already, and we will wait on the work queue to do conversions - which must also take the i_mutex. So that won't work. This was originally exposed by qemu-kvm installing to a raw disk image with a normal sector-63 alignment. I've tested a backport of this patch with qemu, and it does avoid the corruption. It is also quite a lot slower (14 min for package installs, vs. 8 min for well-aligned) but I'll take slow correctness over fast corruption any day. Mingming suggested that we can track outstanding conversions, and wait on those so that non-sparse files won't be affected, and I've implemented that here; unaligned AIO to nonsparse files won't take a perf hit. [tytso@mit.edu: Keep the mutex as a hashed array instead of bloating the ext4 inode] [tytso@mit.edu: Fix up namespace issues so that global variables are protected with an "ext4_" prefix.] Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Fix data corruption with multi-block writepages supportCurt Wohlgemuth2011-02-071-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a corruption problem with the multi-block writepages submittal change for ext4, from commit bd2d0210cf22f2bd0cef72eb97cf94fc7d31d8cc ("ext4: use bio layer instead of buffer layer in mpage_da_submit_io"). (Note that this corruption is not present in 2.6.37 on ext4, because the corruption was detected after the feature was merged in 2.6.37-rc1, and so it was turned off by adding a non-default mount option, mblk_io_submit. With this commit, which hopefully fixes the last of the bugs with this feature, we'll be able to turn on this performance feature by default in 2.6.38, and remove the mblk_io_submit option.) The ext4 code path to bundle multiple pages for writeback in ext4_bio_write_page() had a bug: we should be clearing buffer head dirty flags *before* we submit the bio, not in the completion routine. The patch below was tested on 2.6.37 under KVM with the postgresql script which was submitted by Jon Nelson as documented in commit 1449032be1. Without the patch, I'd hit the corruption problem about 50-70% of the time. With the patch, I executed the script > 100 times with no corruption seen. I also fixed a bug to make sure ext4_end_bio() doesn't dereference the bio after the bio_put() call. Reported-by: Jon Nelson <jnelson@jamponi.net> Reported-by: Matthias Bayer <jackdachef@gmail.com> Signed-off-by: Curt Wohlgemuth <curtw@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
* ext4: test the correct variable in ext4_init_pageio()Dan Carpenter2011-01-101-1/+1
| | | | | | | | | This is a copy and paste error. The intent was to check "io_page_cachep". We tested "io_page_cachep" earlier. Signed-off-by: Dan Carpenter <error27@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use kmem_cache_zalloc() in ext4_init_io_end()Jesper Juhl2010-12-191-4/+1
| | | | | | | | | | | | | | | | | Use advantage of kmem_cache_zalloc() to remove a memset() call in ext4_init_io_end() and save a few bytes. Before: [jj@dragon linux-2.6]$ size fs/ext4/page-io.o text data bss dec hex filename 3016 0 624 3640 e38 fs/ext4/page-io.o After: [jj@dragon linux-2.6]$ size fs/ext4/page-io.o text data bss dec hex filename 3000 0 624 3624 e28 fs/ext4/page-io.o Signed-off-by: Jesper Juhl <jj@chaosbits.net> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix setting random pages PageUptodateMarkus Trippelsdorf2010-11-171-2/+2
| | | | | | | | | | | | | | | | | | | ext4_end_bio calls put_page and kmem_cache_free before calling SetPageUpdate(). This can result in setting the PageUptodate bit on random pages and causes the following BUG: BUG: Bad page state in process rm pfn:52e54 page:ffffea0001222260 count:0 mapcount:0 mapping: (null) index:0x0 arch kernel: page flags: 0x4000000000000008(uptodate) Fix the problem by moving put_io_page() after the SetPageUpdate() call. Thanks to Hugh Dickins for analyzing this problem. Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Tested-by: Markus Trippelsdorf <markus@trippelsdorf.de> Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix potential race when freeing ext4_io_page structuresTheodore Ts'o2010-11-081-23/+15
| | | | | | | Use an atomic_t and make sure we don't free the structure while we might still be submitting I/O for that page. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: handle writeback of inodes which are being freedTheodore Ts'o2010-11-081-25/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following BUG can occur when an inode which is getting freed when it still has dirty pages outstanding, and it gets deleted (in this because it was the target of a rename). In ordered mode, we need to make sure the data pages are written just in case we crash before the rename (or unlink) is committed. If the inode is being freed then when we try to igrab the inode, we end up tripping the BUG_ON at fs/ext4/page-io.c:146. To solve this problem, we need to keep track of the number of io callbacks which are pending, and avoid destroying the inode until they have all been completed. That way we don't have to bump the inode count to keep the inode from being destroyed; an approach which doesn't work because the count could have already been dropped down to zero before the inode writeback has started (at which point we're not allowed to bump the count back up to 1, since it's already started getting freed). Thanks to Dave Chinner for suggesting this approach, which is also used by XFS. kernel BUG at /scratch_space/linux-2.6/fs/ext4/page-io.c:146! Call Trace: [<ffffffff811075b1>] ext4_bio_write_page+0x172/0x307 [<ffffffff811033a7>] mpage_da_submit_io+0x2f9/0x37b [<ffffffff811068d7>] mpage_da_map_and_submit+0x2cc/0x2e2 [<ffffffff811069b3>] mpage_add_bh_to_extent+0xc6/0xd5 [<ffffffff81106c66>] write_cache_pages_da+0x2a4/0x3ac [<ffffffff81107044>] ext4_da_writepages+0x2d6/0x44d [<ffffffff81087910>] do_writepages+0x1c/0x25 [<ffffffff810810a4>] __filemap_fdatawrite_range+0x4b/0x4d [<ffffffff810815f5>] filemap_fdatawrite_range+0xe/0x10 [<ffffffff81122a2e>] jbd2_journal_begin_ordered_truncate+0x7b/0xa2 [<ffffffff8110615d>] ext4_evict_inode+0x57/0x24c [<ffffffff810c14a3>] evict+0x22/0x92 [<ffffffff810c1a3d>] iput+0x212/0x249 [<ffffffff810bdf16>] dentry_iput+0xa1/0xb9 [<ffffffff810bdf6b>] d_kill+0x3d/0x5d [<ffffffff810be613>] dput+0x13a/0x147 [<ffffffff810b990d>] sys_renameat+0x1b5/0x258 [<ffffffff81145f71>] ? _atomic_dec_and_lock+0x2d/0x4c [<ffffffff810b2950>] ? cp_new_stat+0xde/0xea [<ffffffff810b29c1>] ? sys_newlstat+0x2d/0x38 [<ffffffff810b99c6>] sys_rename+0x16/0x18 [<ffffffff81002a2b>] system_call_fastpath+0x16/0x1b Reported-by: Nick Bowler <nbowler@elliptictech.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Tested-by: Nick Bowler <nbowler@elliptictech.com>
* ext4: rename {exit,init}_ext4_*() to ext4_{exit,init}_*()Theodore Ts'o2010-10-271-2/+2
| | | | | | This is a cleanup to avoid namespace leaks out of fs/ext4 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use bio layer instead of buffer layer in mpage_da_submit_ioTheodore Ts'o2010-10-271-0/+430
Call the block I/O layer directly instad of going through the buffer layer. This should give us much better performance and scalability, as well as lowering our CPU utilization when doing buffered writeback. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>