- 13 Jun, 2013 5 commits
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Paul Gortmaker authored
While trying to debug an an issue under extreme I/O loading on preempt-rt kernels, the following backtrace was observed via SysRQ output: rm D ffff8802203afbc0 4600 4878 4748 0x00000000 ffff8802217bfb78 0000000000000082 ffff88021fc2bb80 ffff88021fc2bb80 ffff88021fc2bb80 ffff8802217bffd8 ffff8802217bffd8 ffff8802217bffd8 ffff88021f1d4c80 ffff88021fc2bb80 ffff8802217bfb88 ffff88022437b000 Call Trace: [<ffffffff8172dc34>] schedule+0x24/0x70 [<ffffffff81225b5d>] jbd2_log_wait_commit+0xbd/0x140 [<ffffffff81060390>] ? __init_waitqueue_head+0x50/0x50 [<ffffffff81223635>] jbd2_log_do_checkpoint+0xf5/0x520 [<ffffffff81223b09>] __jbd2_log_wait_for_space+0xa9/0x1f0 [<ffffffff8121dc40>] start_this_handle.isra.10+0x2e0/0x530 [<ffffffff81060390>] ? __init_waitqueue_head+0x50/0x50 [<ffffffff8121e0a3>] jbd2__journal_start+0xc3/0x110 [<ffffffff811de7ce>] ? ext4_rmdir+0x6e/0x230 [<ffffffff8121e0fe>] jbd2_journal_start+0xe/0x10 [<ffffffff811f308b>] ext4_journal_start_sb+0x5b/0x160 [<ffffffff811de7ce>] ext4_rmdir+0x6e/0x230 [<ffffffff811435c5>] vfs_rmdir+0xd5/0x140 [<ffffffff8114370f>] do_rmdir+0xdf/0x120 [<ffffffff8105c6b4>] ? task_work_run+0x44/0x80 [<ffffffff81002889>] ? do_notify_resume+0x89/0x100 [<ffffffff817361ae>] ? int_signal+0x12/0x17 [<ffffffff81145d85>] sys_unlinkat+0x25/0x40 [<ffffffff81735f22>] system_call_fastpath+0x16/0x1b What is interesting here, is that we call log_wait_commit, from within wait_for_space, but we are still holding the checkpoint_mutex as it surrounds mostly the whole of wait_for_space. And then, as we are waiting, journal_commit_transaction can run, and if the JBD2_FLUSHED bit is set, then we will also try to take the same checkpoint_mutex. It seems that we need to drop the checkpoint_mutex while sitting in jbd2_log_wait_commit, if we want to guarantee that progress can be made by jbd2_journal_commit_transaction(). There does not seem to be anything preempt-rt specific about this, other then perhaps increasing the odds of it happening. Signed-off-by:
Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by:
"Theodore Ts'o" <tytso@mit.edu>
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Paul Gortmaker authored
The state lock is taken after we are doing an assert on the state value, not before. So we might in fact be doing an assert on a transient value. Ensure the state check is within the scope of the state lock being taken. Signed-off-by:
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Dmitry Monakhov authored
If filesystem was aborted after inode's write back is complete but before its metadata was updated we may return success results in data loss. In order to handle fs abort correctly we have to check fs state once we discover that it is in MS_RDONLY state Test case: http://patchwork.ozlabs.org/patch/244297Reviewed-by:
Jan Kara <jack@suse.cz> Signed-off-by:
Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by:
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Dmitry Monakhov authored
Inode's data or non journaled quota may be written w/o jounral so we _must_ send a barrier at the end of ext4_sync_fs. But it can be skipped if journal commit will do it for us. Also fix data integrity for nojournal mode. Signed-off-by:
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Dmitry Monakhov authored
Current implementation of jbd2_journal_force_commit() is suboptimal because result in empty and useless commits. But callers just want to force and wait any unfinished commits. We already have jbd2_journal_force_commit_nested() which does exactly what we want, except we are guaranteed that we do not hold journal transaction open. Signed-off-by:
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- 12 Jun, 2013 2 commits
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Theodore Ts'o authored
Commit 18888cf0: "ext4: speed up truncate/unlink by not using bforget() unless needed" removed the use of EXT4_FREE_BLOCKS_FORGET in the most important codepath for file systems using extents, but a similar optimization also can be done for file systems using indirect blocks, and for the two special cases in the ext4 extents code. Cc: Andrey Sidorov <qrxd43@motorola.com> Signed-off-by:
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Theodore Ts'o authored
For a file systems with a very large number of block groups, if all of the block group bitmaps are in memory and the file system is relatively badly fragmented, it's possible ext4_mb_regular_allocator() to take a long time trying to find a good match. This is especially true if the tuning parameter mb_max_to_scan has been sent to a very large number. So add a cond_resched() to avoid soft lockup warnings and to provide better system responsiveness. For ext4_free_blocks(), if we are deleting a large range of blocks, and data=journal is enabled so that EXT4_FREE_BLOCKS_FORGET is passed, the loop to call sb_find_get_block() and to call ext4_forget() can take over 10-15 milliseocnds or more. So it's better to add a cond_resched() here a well. Signed-off-by:
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- 06 Jun, 2013 5 commits
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Theodore Ts'o authored
Rename ext4_da_writepages() to ext4_writepages() and use it for all modes. We still need to iterate over all the pages in the case of data=journalling, but in the case of nodelalloc/data=ordered (which is what file systems mounted using ext3 backwards compatibility will use) this will allow us to use a much more efficient I/O submission path. Signed-off-by: -
Theodore Ts'o authored
The test_root() function could potentially loop forever due to overflow issues. So rewrite test_root() to avoid this issue; as a bonus, it is 38% faster when benchmarked via a test loop: int main(int argc, char **argv) { int i; for (i = 0; i < 1 << 24; i++) { if (test_root(i, 7)) printf("%d\n", i); } } Signed-off-by: -
Theodore Ts'o authored
The group number passed to ext4_get_group_info() should be valid, but let's add an assert to check this before we start creating a pointer based on that group number and dereferencing it. Signed-off-by: -
Theodore Ts'o authored
Check the group number for sanity earilier, before calling routines such as ext4_bg_has_super() or ext4_group_overhead_blocks(). Reported-by:
Jonathan Salwan <jonathan.salwan@gmail.com> Signed-off-by:
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Theodore Ts'o authored
The bio_alloc() function can return NULL if the memory allocation fails. So we need to check for this. Signed-off-by:
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- 04 Jun, 2013 26 commits
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Jan Kara authored
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:
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Jan Kara authored
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:
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Jan Kara authored
We don't have to wait for unwritten extent conversion in ext4_ind_direct_IO() as all writes that happened before DIO are flushed by the generic code and extent conversion has happened before we cleared PageWriteback bit. Reviewed-by:
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Jan Kara authored
After removal of ext4_flush_unwritten_io() call, ext4_file_sync() doesn't need i_mutex anymore. Forcing of transaction commits doesn't need i_mutex as there's nothing inode specific in that code apart from grabbing transaction ids from the inode. So remove the lock. Reviewed-by:
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Jan Kara authored
Just use the generic function instead of duplicating it. We only need to reshuffle the read-only check a bit (which is there to prevent writing to a filesystem which has been remounted read-only after error I assume). Reviewed-by:
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Jan Kara authored
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:
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Jan Kara authored
Make sure extent conversion after DIO happens while i_dio_count is still elevated so that inode_dio_wait() waits until extent conversion is done. This removes the need for explicit waiting for extent conversion in some cases. Reviewed-by:
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Jan Kara authored
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:
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Jan Kara authored
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:
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Jan Kara authored
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:
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Jan Kara authored
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:
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Jan Kara authored
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:
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Jan Kara authored
We limit the number of blocks written in a single loop of ext4_da_writepages() to 64 when inode uses indirect blocks. That is unnecessary as credit estimates for mapping logically continguous run of blocks is rather low even for inode with indirect blocks. So just lift this limitation and properly calculate the number of necessary credits. This better credit estimate will also later allow us to always write at least a single page in one iteration. Reviewed-by:
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Jan Kara authored
ext4_ind_trans_blocks() wrongly used 'chunk' argument to decide whether blocks mapped are logically contiguous. That is wrong since the argument informs whether the blocks are physically contiguous. As the blocks mapped are always logically contiguous and that's all ext4_ind_trans_blocks() cares about, just remove the 'chunk' argument. Reviewed-by:
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Jan Kara authored
This attribute is now unused so deprecate it. We still show the old default value to keep some compatibility but we don't allow writing to that attribute anymore. Signed-off-by:
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Jan Kara authored
Writeback code got better in how it submits IO and now the number of pages requested to be written is usually higher than original 1024. The number is now dynamically computed based on observed throughput and is set to be about 0.5 s worth of writeback. E.g. on ordinary SATA drive this ends up somewhere around 10000 as my testing shows. So remove the unnecessary smarts from ext4_da_writepages(). Reviewed-by:
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Jan Kara authored
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Jan Kara authored
In some cases we cannot start a transaction because of locking constraints and passing started transaction into those places is not handy either because we could block transaction commit for too long. Transaction reservation is designed to solve these issues. It reserves a handle with given number of credits in the journal and the handle can be later attached to the running transaction without blocking on commit or checkpointing. Reserved handles do not block transaction commit in any way, they only reduce maximum size of the running transaction (because we have to always be prepared to accomodate request for attaching reserved handle). Signed-off-by:
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Jan Kara authored
j_wait_logspace and j_wait_checkpoint are unused. Remove them. Reviewed-by:
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Jan Kara authored
jbd2_journal_extend() first checked whether transaction can accept extending handle with more credits and then added credits to t_outstanding_credits. This can race with start_this_handle() adding another handle to a transaction and thus overbooking a transaction. Make jbd2_journal_extend() use atomic_add_return() to close the race. Reviewed-by:
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Jan Kara authored
__jbd2_log_space_left() and jbd_space_needed() were kind of odd. jbd_space_needed() accounted also credits needed for currently committing transaction while it didn't account for credits needed for control blocks. __jbd2_log_space_left() then accounted for control blocks as a fraction of free space. Since results of these two functions are always only compared against each other, this works correct but is somewhat strange. Move the estimates so that jbd_space_needed() returns number of blocks needed for a transaction including control blocks and __jbd2_log_space_left() returns free space in the journal (with the committing transaction already subtracted). Rename functions to jbd2_log_space_left() and jbd2_space_needed() while we are changing them. Reviewed-by:
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Jan Kara authored
The comment about credit estimates isn't true anymore. We do what the comment describes now. Reviewed-by:
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Jan Kara authored
Currently when we add a buffer to a transaction, we wait until the buffer is removed from BJ_Shadow list (so that we prevent any changes to the buffer that is just written to the journal). This can take unnecessarily long as a lot happens between the time the buffer is submitted to the journal and the time when we remove the buffer from BJ_Shadow list. (e.g. We wait for all data buffers in the transaction, we issue a cache flush, etc.) Also this creates a dependency of do_get_write_access() on transaction commit (namely waiting for data IO to complete) which we want to avoid when implementing transaction reservation. So we modify commit code to set new BH_Shadow flag when temporary shadowing buffer is created and we clear that flag once IO on that buffer is complete. This allows do_get_write_access() to wait only for BH_Shadow bit and thus removes the dependency on data IO completion. Reviewed-by:
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Jan Kara authored
Similarly as for metadata buffers, also log descriptor buffers don't really need the journal head. So strip it and remove BJ_LogCtl list. Reviewed-by:
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Jan Kara authored
When writing metadata to the journal, we create temporary buffer heads for that task. We also attach journal heads to these buffer heads but the only purpose of the journal heads is to keep buffers linked in transaction's BJ_IO list. We remove the need for journal heads by reusing buffer_head's b_assoc_buffers list for that purpose. Also since BJ_IO list is just a temporary list for transaction commit, we use a private list in jbd2_journal_commit_transaction() for that thus removing BJ_IO list from transaction completely. Reviewed-by:
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Jan Kara authored
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:
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- 31 May, 2013 2 commits
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Jan Kara authored
The arithmetics adding delalloc blocks to the number of used blocks in ext4_getattr() can easily overflow on 32-bit archs as we first multiply number of blocks by blocksize and then divide back by 512. Make the arithmetics more clever and also use proper type (unsigned long long instead of unsigned long). Signed-off-by:
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Jan Kara authored
On 32-bit architectures with 32-bit sector_t computation of data offset in ext4_xattr_fiemap() can overflow resulting in reporting bogus data location. Fix the problem by typing block number to proper type before shifting. Signed-off-by:
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