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* ext4: fix assertion in ext4_add_complete_io()Jan Kara2013-10-161-2/+3
| | | | | | | | | | It doesn't make sense to require io_end->handle when we are in nojournal mode. So update the assertion accordingly to avoid false warnings from ext4_add_complete_io(). Reported-by: Eric Whitney <enwlinux@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* direct-io: Implement generic deferred AIO completionsChristoph Hellwig2013-09-041-23/+7
| | | | | | | | | | | | | | | | | | | | | | | Add support to the core direct-io code to defer AIO completions to user context using a workqueue. This replaces opencoded and less efficient code in XFS and ext4 (we save a memory allocation for each direct IO) and will be needed to properly support O_(D)SYNC for AIO. The communication between the filesystem and the direct I/O code requires a new buffer head flag, which is a bit ugly but not avoidable until the direct I/O code stops abusing the buffer_head structure for communicating with the filesystems. Currently this creates a per-superblock unbound workqueue for these completions, which is taken from an earlier patch by Jan Kara. I'm not really convinced about this use and would prefer a "normal" global workqueue with a high concurrency limit, but this needs further discussion. JK: Fixed ext4 part, dynamic allocation of the workqueue. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* ext4: rate limit printk in buffer_io_error()Anatol Pomozov2013-07-111-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | If there are a lot of outstanding buffered IOs when a device is taken offline (due to hardware errors etc), ext4_end_bio prints out a message for each failed logical block. While this is desirable, we see thousands of such lines being printed out before the serial console gets overwhelmed, causing ext4_end_bio() wait for the printk to complete. This in itself isn't a disaster, except for the detail that this function is being called with the queue lock held. This causes any other function in the block layer to spin on its spin_lock_irqsave while the serial console is draining. If NMI watchdog is enabled on this machine then it eventually comes along and shoots the machine in the head. The end result is that losing any one disk causes the machine to go down. This patch rate limits the printk to bandaid around the problem. Tested: xfstests Change-Id: I8ab5690dcf4f3a67e78be147d45e489fdf4a88d8 Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix warning in ext4_evict_inode()Jan Kara2013-07-101-13/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following race can lead to ext4_evict_inode() seeing i_ioend_count > 0 and thus triggering a sanity check warning: CPU1 CPU2 ext4_end_bio() ext4_evict_inode() ext4_finish_bio() end_page_writeback(); truncate_inode_pages() evict page WARN_ON(i_ioend_count > 0); ext4_put_io_end_defer() ext4_release_io_end() dec i_ioend_count This is possible use-after-free bug since we decrement i_ioend_count in possibly released inode. Since i_ioend_count is used only for sanity checks one possible solution would be to just remove it but for now I'd like to keep those sanity checks to help debugging the new ext4 writeback code. This patch changes ext4_end_bio() to call ext4_put_io_end_defer() before ext4_finish_bio() in the shortcut case when unwritten extent conversion isn't needed. In that case we don't need the io_end so we are safe to drop it early. Reported-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: add check to io_submit_init_bioTheodore Ts'o2013-06-061-0/+2
| | | | | | | The bio_alloc() function can return NULL if the memory allocation fails. So we need to check for this. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove ext4_ioend_wait()Jan Kara2013-06-041-19/+0
| | | | | | | | | | | | | Now that we clear PageWriteback after extent conversion, there's no need to wait for io_end processing in ext4_evict_inode(). Running AIO/DIO keeps file reference until aio_complete() is called so ext4_evict_inode() cannot be called. For io_end structures resulting from buffered IO waiting is happening because we wait for PageWriteback in truncate_inode_pages(). Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: don't wait for extent conversion in ext4_punch_hole()Jan Kara2013-06-041-16/+0
| | | | | | | | | | | | | | We don't have to wait for extent conversion in ext4_punch_hole() as buffered IO for the punched range has been flushed and waited upon (thus all extent conversions for that range have completed). Also we wait for all DIO to finish using inode_dio_wait() so there cannot be any extent conversions pending due to direct IO. Also remove ext4_flush_unwritten_io() since it's unused now. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove wait for unwritten extent conversion from ext4_truncate()Jan Kara2013-06-041-1/+8
| | | | | | | | | | | | | | Since PageWriteback bit is now cleared after extents are converted from unwritten to written ones, we have full exclusion of writeback path from truncate (truncate_inode_pages() waits for PageWriteback bits to get cleared on all invalidated pages). Exclusion from DIO path is achieved by inode_dio_wait() call in ext4_setattr(). So there's no need to wait for extent convertion in ext4_truncate() anymore. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: defer clearing of PageWriteback after extent conversionJan Kara2013-06-041-59/+79
| | | | | | | | | | | | | | | | | | | | | | | Currently PageWriteback bit gets cleared from put_io_page() called from ext4_end_bio(). This is somewhat inconvenient as extent tree is not fully updated at that time (unwritten extents are not marked as written) so we cannot read the data back yet. This design was dictated by lock ordering as we cannot start a transaction while PageWriteback bit is set (we could easily deadlock with ext4_da_writepages()). But now that we use transaction reservation for extent conversion, locking issues are solved and we can move PageWriteback bit clearing after extent conversion is done. As a result we can remove wait for unwritten extent conversion from ext4_sync_file() because it already implicitely happens through wait_on_page_writeback(). We implement deferring of PageWriteback clearing by queueing completed bios to appropriate io_end and processing all the pages when io_end is going to be freed instead of at the moment ext4_io_end() is called. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: split extent conversion lists to reserved & unreserved partsJan Kara2013-06-041-23/+42
| | | | | | | | | | | | Now that we have extent conversions with reserved transaction, we have to prevent extent conversions without reserved transaction (from DIO code) to block these (as that would effectively void any transaction reservation we did). So split lists, work items, and work queues to reserved and unreserved parts. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use transaction reservation for extent conversion in ext4_end_ioJan Kara2013-06-041-3/+8
| | | | | | | | | | | | | | Later we would like to clear PageWriteback bit only after extent conversion from unwritten to written extents is performed. However it is not possible to start a transaction after PageWriteback is set because that violates lock ordering (and is easy to deadlock). So we have to reserve a transaction before locking pages and sending them for IO and later we use the transaction for extent conversion from ext4_end_io(). Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove buffer_uninit handlingJan Kara2013-06-041-4/+0
| | | | | | | | | | | There isn't any need for setting BH_Uninit on buffers anymore. It was only used to signal we need to mark io_end as needing extent conversion in add_bh_to_extent() but now we can mark the io_end directly when mapping extent. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: restructure writeback pathJan Kara2013-06-041-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | There are two issues with current writeback path in ext4. For one we don't necessarily map complete pages when blocksize < pagesize and thus needn't do any writeback in one iteration. We always map some blocks though so we will eventually finish mapping the page. Just if writeback races with other operations on the file, forward progress is not really guaranteed. The second problem is that current code structure makes it hard to associate all the bios to some range of pages with one io_end structure so that unwritten extents can be converted after all the bios are finished. This will be especially difficult later when io_end will be associated with reserved transaction handle. We restructure the writeback path to a relatively simple loop which first prepares extent of pages, then maps one or more extents so that no page is partially mapped, and once page is fully mapped it is submitted for IO. We keep all the mapping and IO submission information in mpage_da_data structure to somewhat reduce stack usage. Resulting code is somewhat shorter than the old one and hopefully also easier to read. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use io_end for multiple biosJan Kara2013-06-041-45/+76
| | | | | | | | | | | | | | | Change writeback path to create just one io_end structure for the extent to which we submit IO and share it among bios writing that extent. This prevents needless splitting and joining of unwritten extents when they cannot be submitted as a single bio. Bugs in ENOMEM handling found by Linux File System Verification project (linuxtesting.org) and fixed by Alexey Khoroshilov <khoroshilov@ispras.ru>. CC: Alexey Khoroshilov <khoroshilov@ispras.ru> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* Merge tag 'ext4_for_linus_stable' of ↵Linus Torvalds2013-05-141-76/+45
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 Pull ext4 update from Ted Ts'o: "Fixed regressions (two stability regressions and a performance regression) introduced during the 3.10-rc1 merge window. Also included is a bug fix relating to allocating blocks after resizing an ext3 file system when using the ext4 file system driver" * tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: jbd,jbd2: fix oops in jbd2_journal_put_journal_head() ext4: revert "ext4: use io_end for multiple bios" ext4: limit group search loop for non-extent files ext4: fix fio regression
| * ext4: revert "ext4: use io_end for multiple bios"Theodore Ts'o2013-05-111-76/+45
| | | | | | | | | | | | | | | | | | | | | | This reverts commit 4eec708d263f0ee10861d69251708a225b64cac7. Multiple users have reported crashes which is apparently caused by this commit. Thanks to Dmitry Monakhov for bisecting it. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: Dmitry Monakhov <dmonakhov@openvz.org> Cc: Jan Kara <jack@suse.cz>
* | aio: don't include aio.h in sched.hKent Overstreet2013-05-071-0/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | Faster kernel compiles by way of fewer unnecessary includes. [akpm@linux-foundation.org: fix fallout] [akpm@linux-foundation.org: fix build] Signed-off-by: Kent Overstreet <koverstreet@google.com> Cc: Zach Brown <zab@redhat.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jens Axboe <axboe@kernel.dk> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> Reviewed-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ext4: clear buffer_uninit flag when submitting IOJan Kara2013-04-121-1/+1
| | | | | | | | | | | | Currently noone cleared buffer_uninit flag. This results in writeback needlessly marking io_end as needing extent conversion scanning extent tree for extents to convert. So clear the buffer_uninit flag once the buffer is submitted for IO and the flag is transformed into EXT4_IO_END_UNWRITTEN flag. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
* ext4: use io_end for multiple biosJan Kara2013-04-111-46/+75
| | | | | | | | | | | | Change writeback path to create just one io_end structure for the extent to which we submit IO and share it among bios writing that extent. This prevents needless splitting and joining of unwritten extents when they cannot be submitted as a single bio. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Dmitry Monakhov <dmonakhov@openvz.org> Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
* ext4: make ext4_bio_write_page() use BH_Async_Write flagsJan Kara2013-04-111-86/+77
| | | | | | | | | | | | | | | | | | | | | | | | | So far ext4_bio_write_page() attached all the pages to ext4_io_end structure. This makes that structure pretty heavy (1 KB for pointers + 16 bytes per page attached to the bio). Also later we would like to share ext4_io_end structure among several bios in case IO to a single extent needs to be split among several bios and pointing to pages from ext4_io_end makes this complex. We remove page pointers from ext4_io_end and use pointers from bio itself instead. This isn't as easy when blocksize < pagesize because then we can have several bios in flight for a single page and we have to be careful when to call end_page_writeback(). However this is a known problem already solved by block_write_full_page() / end_buffer_async_write() so we mimic its behavior here. We mark buffers going to disk with BH_Async_Write flag and in ext4_bio_end_io() we check whether there are any buffers with BH_Async_Write flag left. If there are not, we can call end_page_writeback(). Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Dmitry Monakhov <dmonakhov@openvz.org> Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
* ext4: fix ext4_evict_inode() racing against workqueue processing codeTheodore Ts'o2013-03-201-1/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 84c17543ab56 (ext4: move work from io_end to inode) triggered a regression when running xfstest #270 when the file system is mounted with dioread_nolock. The problem is that after ext4_evict_inode() calls ext4_ioend_wait(), this guarantees that last io_end structure has been freed, but it does not guarantee that the workqueue structure, which was moved into the inode by commit 84c17543ab56, is actually finished. Once ext4_flush_completed_IO() calls ext4_free_io_end() on CPU #1, this will allow ext4_ioend_wait() to return on CPU #2, at which point the evict_inode() codepath can race against the workqueue code on CPU #1 accessing EXT4_I(inode)->i_unwritten_work to find the next item of work to do. Fix this by calling cancel_work_sync() in ext4_ioend_wait(), which will be renamed ext4_ioend_shutdown(), since it is only used by ext4_evict_inode(). Also, move the call to ext4_ioend_shutdown() until after truncate_inode_pages() and filemap_write_and_wait() are called, to make sure all dirty pages have been written back and flushed from the page cache first. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<c01dda6a>] cwq_activate_delayed_work+0x3b/0x7e *pdpt = 0000000030bc3001 *pde = 0000000000000000 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: Pid: 6, comm: kworker/u:0 Not tainted 3.8.0-rc3-00013-g84c1754-dirty #91 Bochs Bochs EIP: 0060:[<c01dda6a>] EFLAGS: 00010046 CPU: 0 EIP is at cwq_activate_delayed_work+0x3b/0x7e EAX: 00000000 EBX: 00000000 ECX: f505fe54 EDX: 00000000 ESI: ed5b697c EDI: 00000006 EBP: f64b7e8c ESP: f64b7e84 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 CR0: 8005003b CR2: 00000000 CR3: 30bc2000 CR4: 000006f0 DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 DR6: ffff0ff0 DR7: 00000400 Process kworker/u:0 (pid: 6, ti=f64b6000 task=f64b4160 task.ti=f64b6000) Stack: f505fe00 00000006 f64b7e9c c01de3d7 f6435540 00000003 f64b7efc c01def1d f6435540 00000002 00000000 0000008a c16d0808 c040a10b c16d07d8 c16d08b0 f505fe00 c16d0780 00000000 00000000 ee153df4 c1ce4a30 c17d0e30 00000000 Call Trace: [<c01de3d7>] cwq_dec_nr_in_flight+0x71/0xfb [<c01def1d>] process_one_work+0x5d8/0x637 [<c040a10b>] ? ext4_end_bio+0x300/0x300 [<c01e3105>] worker_thread+0x249/0x3ef [<c01ea317>] kthread+0xd8/0xeb [<c01e2ebc>] ? manage_workers+0x4bb/0x4bb [<c023a370>] ? trace_hardirqs_on+0x27/0x37 [<c0f1b4b7>] ret_from_kernel_thread+0x1b/0x28 [<c01ea23f>] ? __init_kthread_worker+0x71/0x71 Code: 01 83 15 ac ff 6c c1 00 31 db 89 c6 8b 00 a8 04 74 12 89 c3 30 db 83 05 b0 ff 6c c1 01 83 15 b4 ff 6c c1 00 89 f0 e8 42 ff ff ff <8b> 13 89 f0 83 05 b8 ff 6c c1 6c c1 00 31 c9 83 EIP: [<c01dda6a>] cwq_activate_delayed_work+0x3b/0x7e SS:ESP 0068:f64b7e84 CR2: 0000000000000000 ---[ end trace a1923229da53d8a4 ]--- Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: Jan Kara <jack@suse.cz>
* ext4: fix possible use-after-free with AIOJan Kara2013-01-291-5/+4
| | | | | | | | | | | | | Running AIO is pinning inode in memory using file reference. Once AIO is completed using aio_complete(), file reference is put and inode can be freed from memory. So we have to be sure that calling aio_complete() is the last thing we do with the inode. CC: stable@vger.kernel.org Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove unused variable flagsLukas Czerner2013-01-281-1/+0
| | | | | | | | | Remove unused variable flags from dump_completed_IO(). The code is only exercised when EXT4FS_DEBUG is defined. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
* ext4: Make ext4_bio_writepage() handle unprepared buffersJan Kara2013-01-281-8/+9
| | | | | | | | | | | | | | | | | So far ext4_bio_writepage() unconditionally cleared dirty bit on all buffers underlying the page. That implicitely assumes we can write all buffers. So far that is true because callers call into ext4_bio_writepage() make sure all buffers in the page are mapped but: a) it's a data corruption bug waiting to happen b) in data=ordered mode when blocksize < pagesize we do need to write pages that may have only some of dirty buffers mapped. So change ext4_bio_writepage() to skip buffers that cannot be written without clearing their dirty bit. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: simplify list handling in ext4_do_flush_completed_IO()Jan Kara2013-01-281-17/+1
| | | | | | | | | | | | The function splices i_completed_io_list to its private list first. From that moment on we don't need any lock for working with io_end structures because all io_end structure on the list are only our own. So we can remove the other two lists in the function and free io_end immediately after we are done with it. CC: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: move work from io_end to inodeJan Kara2013-01-281-24/+9
| | | | | | | | | | | It does not make much sense to have struct work in ext4_io_end_t because we always use it for only one ext4_io_end_t per inode (the first one in the i_completed_io list). So just move the structure to inode itself. This also allows for a small simplification in processing io_end structures. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use redirty_page_for_writepage() in ext4_bio_write_page()Jan Kara2013-01-281-3/+4
| | | | | | | | | | | | | When we cannot write a page we should use redirty_page_for_writepage() instead of plain set_page_dirty(). That tells writeback code we have problems, redirties only the page (redirtying buffers is not needed), and updates mm accounting of failed page writes. Also move clearing of buffer dirty flag after io_submit_add_bh(). At that moment we are sure buffer will be going to disk. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Always use ext4_bio_write_page() for writeoutJan Kara2013-01-281-2/+0
| | | | | | | | | | Currently we sometimes used block_write_full_page() and sometimes ext4_bio_write_page() for writeback (depending on mount options and call path). Let's always use ext4_bio_write_page() to simplify things a bit. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: rationalize ext4_extents.h inclusionTheodore Ts'o2012-11-281-1/+0
| | | | | | | | | | | | | | | | | | | | | | Previously, ext4_extents.h was being included at the end of ext4.h, which was bad for a number of reasons: (a) it was not being included in the expected place, and (b) it caused the header to be included multiple times. There were #ifdef's to prevent this from causing any problems, but it still was unnecessary. By moving the function declarations that were in ext4_extents.h to ext4.h, which is standard practice for where the function declarations for the rest of ext4.h can be found, we can remove ext4_extents.h from being included in ext4.h at all, and then we can only include ext4_extents.h where it is needed in ext4's source files. It should be possible to move a few more things into ext4.h, and further reduce the number of source files that need to #include ext4_extents.h, but that's a cleanup for another day. Reported-by: Sachin Kamat <sachin.kamat@linaro.org> Reported-by: Wei Yongjun <weiyj.lk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use 'inode' variable that is already dereferencedAnatol Pomozov2012-11-081-1/+1
| | | | | | | | Tested: xfs tests Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix ext4_flush_completed_IO wait semanticsDmitry Monakhov2012-10-051-4/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BUG #1) All places where we call ext4_flush_completed_IO are broken because buffered io and DIO/AIO goes through three stages 1) submitted io, 2) completed io (in i_completed_io_list) conversion pended 3) finished io (conversion done) And by calling ext4_flush_completed_IO we will flush only requests which were in (2) stage, which is wrong because: 1) punch_hole and truncate _must_ wait for all outstanding unwritten io regardless to it's state. 2) fsync and nolock_dio_read should also wait because there is a time window between end_page_writeback() and ext4_add_complete_io() As result integrity fsync is broken in case of buffered write to fallocated region: fsync blkdev_completion ->filemap_write_and_wait_range ->ext4_end_bio ->end_page_writeback <-- filemap_write_and_wait_range return ->ext4_flush_completed_IO sees empty i_completed_io_list but pended conversion still exist ->ext4_add_complete_io BUG #2) Race window becomes wider due to the 'ext4: completed_io locking cleanup V4' patch series This patch make following changes: 1) ext4_flush_completed_io() now first try to flush completed io and when wait for any outstanding unwritten io via ext4_unwritten_wait() 2) Rename function to more appropriate name. 3) Assert that all callers of ext4_flush_unwritten_io should hold i_mutex to prevent endless wait Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz>
* ext4: completed_io locking cleanupDmitry Monakhov2012-09-291-58/+113
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Current unwritten extent conversion state-machine is very fuzzy. - For unknown reason it performs conversion under i_mutex. What for? My diagnosis: We already protect extent tree with i_data_sem, truncate and punch_hole should wait for DIO, so the only data we have to protect is end_io->flags modification, but only flush_completed_IO and end_io_work modified this flags and we can serialize them via i_completed_io_lock. Currently all these games with mutex_trylock result in the following deadlock truncate: kworker: ext4_setattr ext4_end_io_work mutex_lock(i_mutex) inode_dio_wait(inode) ->BLOCK DEADLOCK<- mutex_trylock() inode_dio_done() #TEST_CASE1_BEGIN MNT=/mnt_scrach unlink $MNT/file fallocate -l $((1024*1024*1024)) $MNT/file aio-stress -I 100000 -O -s 100m -n -t 1 -c 10 -o 2 -o 3 $MNT/file sleep 2 truncate -s 0 $MNT/file #TEST_CASE1_END Or use 286's xfstests https://github.com/dmonakhov/xfstests/blob/devel/286 This patch makes state machine simple and clean: (1) xxx_end_io schedule final extent conversion simply by calling ext4_add_complete_io(), which append it to ei->i_completed_io_list NOTE1: because of (2A) work should be queued only if ->i_completed_io_list was empty, otherwise the work is scheduled already. (2) ext4_flush_completed_IO is responsible for handling all pending end_io from ei->i_completed_io_list Flushing sequence consists of following stages: A) LOCKED: Atomically drain completed_io_list to local_list B) Perform extents conversion C) LOCKED: move converted io's to to_free list for final deletion This logic depends on context which we was called from. D) Final end_io context destruction NOTE1: i_mutex is no longer required because end_io->flags modification is protected by ei->ext4_complete_io_lock Full list of changes: - Move all completion end_io related routines to page-io.c in order to improve logic locality - Move open coded logic from various xx_end_xx routines to ext4_add_complete_io() - remove EXT4_IO_END_FSYNC - Improve SMP scalability by removing useless i_mutex which does not protect io->flags anymore. - Reduce lock contention on i_completed_io_lock by optimizing list walk. - Rename ext4_end_io_nolock to end4_end_io and make it static - Check flush completion status to ext4_ext_punch_hole(). Because it is not good idea to punch blocks from corrupted inode. Changes since V3 (in request to Jan's comments): Fall back to active flush_completed_IO() approach in order to prevent performance issues with nolocked DIO reads. Changes since V2: Fix use-after-free caused by race truncate vs end_io_work Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix unwritten counter leakageDmitry Monakhov2012-09-281-1/+5
| | | | | | | | | | | | | | | | | ext4_set_io_unwritten_flag() will increment i_unwritten counter, so once we mark end_io with EXT4_END_IO_UNWRITTEN we have to revert it back on error path. - add missed error checks to prevent counter leakage - ext4_end_io_nolock() will clear EXT4_END_IO_UNWRITTEN flag to signal that conversion finished. - add BUG_ON to ext4_free_end_io() to prevent similar leakage in future. Visible effect of this bug is that unaligned aio_stress may deadlock Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: give i_aiodio_unwritten a more appropriate nameDmitry Monakhov2012-09-281-1/+1
| | | | | | | | | AIO/DIO prefix is wrong because it account unwritten extents which also may be scheduled from buffered write endio Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* 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
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