- 14 May, 2012 40 commits
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Dave Chinner authored
Recent event tracing during a debugging session showed that flags that define the IO type for a buffer are leaking into the flags on the buffer incorrectly. Fix the flag exclusion mask in xfs_buf_alloc() to avoid problems that may be caused by such leakage. Signed-off-by:
Dave Chinner <dchinner@redhat.com> Reviewed-by:
Mark Tinguely <tinguely@sgi.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Ben Myers <bpm@sgi.com>
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Dave Chinner authored
With the removal of xfs_rw.h and other changes over time, xfs_bit.h is being included in many files that don't actually need it. Clean up the includes as necessary. Also move the only-used-once xfs_ialloc_find_free() static inline function out of a header file that is widely included to reduce the number of needless dependencies on xfs_bit.h. Signed-off-by:
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Dave Chinner authored
xfs_do_force_shutdown now is the only thing in xfs_rw.c. There is no need to keep it in it's own file anymore, so move it to xfs_fsops.c next to xfs_fs_goingdown() and kill xfs_rw.c. Signed-off-by:
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Dave Chinner authored
The only thing left in xfs_rw.h is a function prototype for an inode function. Move that to xfs_inode.h, and kill xfs_rw.h. Also move the function implementing the prototype from xfs_rw.c to xfs_inode.c so we only have one function left in xfs_rw.c Signed-off-by:
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Dave Chinner authored
This is the only remaining useful function in xfs_rw.h, so move it to a header file responsible for block mapping functions that the callers already include. Soon we can get rid of xfs_rw.h. Signed-off-by:
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Dave Chinner authored
Now that the busy extent tracking has been moved out of the allocation files, clean up the namespace it uses to "xfs_extent_busy" rather than a mix of "xfs_busy" and "xfs_alloc_busy". Signed-off-by: Dave Chinner<dchinner@redhat.com> Reviewed-by:
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Dave Chinner authored
To make it easier to handle userspace code merges, move all the busy extent handling out of the allocation code and into it's own file. The userspace code does not need the busy extent code, so this simplifies the merging of the kernel code into the userspace xfsprogs library. Because the busy extent code has been almost completely rewritten over the past couple of years, also update the copyright on this new file to include the authors that made all those changes. Signed-off-by:
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Dave Chinner authored
Untangle the header file includes a bit by moving the definition of xfs_agino_t to xfs_types.h. This removes the dependency that xfs_ag.h has on xfs_inum.h, meaning we don't need to include xfs_inum.h everywhere we include xfs_ag.h. Signed-off-by:
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Dave Chinner authored
fsstress has a particular effective way of stopping debug XFS kernels. We keep seeing assert failures due finding delayed allocation extents where there should be none. This shows up when extracting extent maps and we are holding all the locks we should be to prevent races, so this really makes no sense to see these errors. After checking that fsstress does not use mmap, it occurred to me that fsstress uses something that no sane application uses - the XFS_IOC_ALLOCSP ioctl interfaces for preallocation. These interfaces do allocation of blocks beyond EOF without using preallocation, and then call setattr to extend and zero the allocated blocks. THe problem here is this is a buffered write, and hence the allocation is a delayed allocation. Unlike the buffered IO path, the allocation and zeroing are not serialised using the IOLOCK. Hence the ALLOCSP operation can race with operations holding the iolock to prevent buffered IO operations from occurring. Signed-off-by:
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Dave Chinner authored
Just about all callers of xfs_buf_read() and xfs_buf_get() use XBF_DONTBLOCK. This is used to make memory allocation use GFP_NOFS rather than GFP_KERNEL to avoid recursion through memory reclaim back into the filesystem. All the blocking get calls in growfs occur inside a transaction, even though they are no part of the transaction, so all allocation will be GFP_NOFS due to the task flag PF_TRANS being set. The blocking read calls occur during log recovery, so they will probably be unaffected by converting to GFP_NOFS allocations. Hence make XBF_DONTBLOCK behaviour always occur for buffers and kill the flag. Signed-off-by:
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Dave Chinner authored
xfs_read_buf() is effectively the same as xfs_trans_read_buf() when called outside a transaction context. The error handling is slightly different in that xfs_read_buf stales the errored buffer it gets back, but there is probably good reason for xfs_trans_read_buf() for doing this. Hence update xfs_trans_read_buf() to the same error handling as xfs_read_buf(), and convert all the callers of xfs_read_buf() to use the former function. We can then remove xfs_read_buf(). Signed-off-by:
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Dave Chinner authored
Buffers are always returned locked from the lookup routines. Hence we don't need to tell the lookup routines to return locked buffers, on to try and lock them. Remove XBF_LOCK from all the callers and from internal buffer cache usage. Signed-off-by:
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Dave Chinner authored
xfs_buf_btoc and friends are simple macros that do basic block to page index conversion and vice versa. These aren't widely used, and we use open coded masking and shifting everywhere else. Hence remove the macros and open code the work they do. Also, use of PAGE_CACHE_{SIZE|SHIFT|MASK} for these macros is now incorrect - we are using pages directly and not the page cache, so use PAGE_{SIZE|MASK|SHIFT} instead. Signed-off-by: -
Dave Chinner authored
Now that we pass block counts everywhere, and index buffers by block number and length in units of blocks, convert the desired IO size into block counts rather than bytes. Convert the code to use block counts, and those that need byte counts get converted at the time of use. Rename the b_desired_count variable to something closer to it's purpose - b_io_length - as it is only used to specify the length of an IO for a subset of the buffer. The only time this is used is for log IO - both writing iclogs and during log recovery. In all other cases, the b_io_length matches b_length, and hence a lot of code confuses the two. e.g. the buf item code uses the io count exclusively when it should be using the buffer length. Fix these apprpriately as they are found. Also, remove the XFS_BUF_{SET_}COUNT() macros that are just wrappers around the desired IO length. They only serve to make the code shouty loud, don't actually add any real value, and are often used incorrectly. Signed-off-by: -
Dave Chinner authored
Now that we pass block counts everywhere, and index buffers by block number, track the length of the buffer in units of blocks rather than bytes. Convert the code to use block counts, and those that need byte counts get converted at the time of use. Also, remove the XFS_BUF_{SET_}SIZE() macros that are just wrappers around the buffer length. They only serve to make the code shouty loud and don't actually add any real value. Signed-off-by: -
Dave Chinner authored
Seeing as we pass block numbers around everywhere in the buffer cache now, it makes no sense to index everything by byte offset. Replace all the byte offset indexing with block number based indexing, and replace all uses of the byte offset with direct conversion from the block index. Signed-off-by:
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Dave Chinner authored
The xfs_buf_get/read API is not consistent in the units it uses, and does not use appropriate or consistent units/types for the variables. Convert the API to use disk addresses and block counts for all buffer get and read calls. Use consistent naming for all the functions and their declarations, and convert the internal functions to use disk addresses and block counts to avoid need to convert them from one type to another and back again. Fix all the callers to use disk addresses and block counts. In many cases, this removes an additional conversion from the function call as the callers already have a block count. Signed-off-by:
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Dave Chinner authored
To replace the alloc/memset pair. Signed-off-by:
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Dave Chinner authored
Because we no longer use the page cache for buffering, there is no direct block number to page offset relationship anymore. xfs_buf_get_pages is still setting up b_offset as if there was some relationship, and that is leading to incorrectly setting up *uncached* buffers that don't overwrite b_offset once they've had pages allocated. For cached buffers, the first block of the buffer is always at offset zero into the allocated memory. This is true for sub-page sized buffers, as well as for multiple-page buffers. For uncached buffers, b_offset is only non-zero when we are associating specific memory to the buffers, and that is set correctly by the code setting up the buffer. Hence remove the setting of b_offset in xfs_buf_get_pages, because it is now always the wrong thing to do. Signed-off-by:
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Dave Chinner authored
If we call xfs_buf_iowait() on a buffer that failed dispatch due to an IO error, it will wait forever for an Io that does not exist. This is hndled in xfs_buf_read, but there is other code that calls xfs_buf_iowait directly that doesn't. Rather than make the call sites have to handle checking for dispatch errors and then checking for completion errors, make xfs_buf_iowait() check for dispatch errors on the buffer before waiting. This means we handle both dispatch and completion errors with one set of error handling at the caller sites. Signed-off-by:
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Dave Chinner authored
When memory allocation fails to add the page array or tht epages to a buffer during xfs_buf_get(), the buffer is left in the cache in a partially initialised state. There is enough state left for the next lookup on that buffer to find the buffer, and for the buffer to then be used without finishing the initialisation. As a result, when an attempt to do IO on the buffer occurs, it fails with EIO because there are no pages attached to the buffer. We cannot remove the buffer from the cache immediately and free it, because there may already be a racing lookup that is blocked on the buffer lock. Hence the moment we unlock the buffer to then free it, the other user is woken and we have a use-after-free situation. To avoid this race condition altogether, allocate the pages for the buffer before we insert it into the cache. This then means that we don't have an allocation failure case to deal after the buffer is already present in the cache, and hence avoid the problem altogether. In most cases we won't have racing inserts for the same buffer, and so won't increase the memory pressure allocation before insertion may entail. Signed-off-by:
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Dave Chinner authored
xfstest 229 exposes a problem with buffered IO, delayed allocation and extent size hints. That is when we do delayed allocation during buffered IO, we reserve space for the extent size hint alignment and allocate the physical space to align the extent, but we do not zero the regions of the extent that aren't written by the write(2) syscall. The result is that we expose stale data in unwritten regions of the extent size hints. There are two ways to fix this. The first is to detect that we are doing unaligned writes, check if there is already a mapping or data over the extent size hint range, and if not zero the page cache first before then doing the real write. This can be very expensive for large extent size hints, especially if the subsequent writes fill then entire extent size before the data is written to disk. The second, and simpler way, is simply to turn off delayed allocation when the extent size hint is set and use preallocation instead. This results in unwritten extents being laid down on disk and so only the written portions will be converted. This matches the behaviour for direct IO, and will also work for the real time device. The disadvantage of this approach is that for small extent size hints we can get file fragmentation, but in general extent size hints are fairly large (e.g. stripe width sized) so this isn't a big deal. Implement the second approach as it is simple and effective. Signed-off-by:
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Dave Chinner authored
Speculative delayed allocation beyond EOF near the maximum supported file offset can result in creating delalloc extents beyond mp->m_maxioffset (8EB). These can never be trimmed during xfs_free_eof_blocks() because they are beyond mp->m_maxioffset, and that results in assert failures in xfs_fs_destroy_inode() due to delalloc blocks still being present. xfstests 071 exposes this problem. Limit speculative delalloc to mp->m_maxioffset to avoid this problem. Signed-off-by:
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Dave Chinner authored
When we are doing speculative delayed allocation beyond EOF, conversion of the region allocated beyond EOF is dependent on the largest free space extent available. If the largest free extent is smaller than the delalloc range, then after allocation we leave a delalloc extent that starts beyond EOF. This extent cannot *ever* be converted by flushing data, and so will remain there until either the EOF moves into the extent or it is truncated away. Hence if xfs_getbmap() runs on such an inode and is asked to return extents beyond EOF, it will assert fail on this extent even though there is nothing xfs_getbmap() can do to convert it to a real extent. Hence we should simply report these delalloc extents rather than assert that there should be none. Signed-off-by:
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Dave Chinner authored
Often mounting small filesystem with small logs will emit a warning such as: XFS (vdb): Invalid block length (0x2000) for buffer during log recovery. This causes tests to randomly fail because this output causes the clean filesystem checks on test completion to think the filesystem is inconsistent. The cause of the error is simply that log recovery is asking for a buffer size that is larger than the log when zeroing the tail. This is because the buffer size is rounded up, and if the right head and tail conditions exist then the buffer size can be larger than the log. Limit the variable size xlog_get_bp() callers to requesting buffers smaller than the log. Signed-off-by:
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Dave Chinner authored
When a partial write inside EOF fails, it can leave delayed allocation blocks lying around because they don't get punched back out. This leads to assert failures like: XFS: Assertion failed: XFS_FORCED_SHUTDOWN(ip->i_mount) || ip->i_delayed_blks == 0, file: fs/xfs/xfs_super.c, line: 847 when evicting inodes from the cache. This can be trivially triggered by xfstests 083, which takes between 5 and 15 executions on a 512 byte block size filesystem to trip over this. Debugging shows a failed write due to ENOSPC calling xfs_vm_write_failed such as: [ 5012.329024] ino 0xa0026: vwf to 0x17000, sze 0x1c85ae and no action is taken on it. This leaves behind a delayed allocation extent that has no page covering it and no data in it: [ 5015.867162] ino 0xa0026: blks: 0x83 delay blocks 0x1, size 0x2538c0 [ 5015.868293] ext 0: off 0x4a, fsb 0x50306, len 0x1 [ 5015.869095] ext 1: off 0x4b, fsb 0x7899, len 0x6b [ 5015.869900] ext 2: off 0xb6, fsb 0xffffffffe0008, len 0x1 ^^^^^^^^^^^^^^^ [ 5015.871027] ext 3: off 0x36e, fsb 0x7a27, len 0xd [ 5015.872206] ext 4: off 0x4cf, fsb 0x7a1d, len 0xa So the delayed allocation extent is one block long at offset 0x16c00. Tracing shows that a bigger write: xfs_file_buffered_write: size 0x1c85ae offset 0x959d count 0x1ca3f ioflags allocates the block, and then fails with ENOSPC trying to allocate the last block on the page, leading to a failed write with stale delalloc blocks on it. Because we've had an ENOSPC when trying to allocate 0x16e00, it means that we are never goinge to call ->write_end on the page and so the allocated new buffer will not get marked dirty or have the buffer_new state cleared. In other works, what the above write is supposed to end up with is this mapping for the page: +------+------+------+------+------+------+------+------+ UMA UMA UMA UMA UMA UMA UND FAIL where: U = uptodate M = mapped N = new A = allocated D = delalloc FAIL = block we ENOSPC'd on. and the key point being the buffer_new() state for the newly allocated delayed allocation block. Except it doesn't - we're not marking buffers new correctly. That buffer_new() problem goes back to the xfs_iomap removal days, where xfs_iomap() used to return a "new" status for any map with newly allocated blocks, so that __xfs_get_blocks() could call set_buffer_new() on it. We still have the "new" variable and the check for it in the set_buffer_new() logic - except we never set it now! Hence that newly allocated delalloc block doesn't have the new flag set on it, so when the write fails we cannot tell which blocks we are supposed to punch out. WHy do we need the buffer_new flag? Well, that's because we can have this case: +------+------+------+------+------+------+------+------+ UMD UMD UMD UMD UMD UMD UND FAIL where all the UMD buffers contain valid data from a previously successful write() system call. We only want to punch the UND buffer because that's the only one that we added in this write and it was only this write that failed. That implies that even the old buffer_new() logic was wrong - because it would result in all those UMD buffers on the page having set_buffer_new() called on them even though they aren't new. Hence we shoul donly be calling set_buffer_new() for delalloc buffers that were allocated (i.e. were a hole before xfs_iomap_write_delay() was called). So, fix this set_buffer_new logic according to how we need it to work for handling failed writes correctly. Also, restore the new buffer logic handling for blocks allocated via xfs_iomap_write_direct(), because it should still set the buffer_new flag appropriately for newly allocated blocks, too. SO, now we have the buffer_new() being set appropriately in __xfs_get_blocks(), we can detect the exact delalloc ranges that we allocated in a failed write, and hence can now do a walk of the buffers on a page to find them. Except, it's not that easy. When block_write_begin() fails, it unlocks and releases the page that we just had an error on, so we can't use that page to handle errors anymore. We have to get access to the page while it is still locked to walk the buffers. Hence we have to open code block_write_begin() in xfs_vm_write_begin() to be able to insert xfs_vm_write_failed() is the right place. With that, we can pass the page and write range to xfs_vm_write_failed() and walk the buffers on the page, looking for delalloc buffers that are either new or beyond EOF and punch them out. Handling buffers beyond EOF ensures we still handle the existing case that xfs_vm_write_failed() handles. Of special note is the truncate_pagecache() handling - that only should be done for pages outside EOF - pages within EOF can still contain valid, dirty data so we must not punch them out of the cache. That just leaves the xfs_vm_write_end() failure handling. The only failure case here is that we didn't copy the entire range, and generic_write_end() handles that by zeroing the region of the page that wasn't copied, we don't have to punch out blocks within the file because they are guaranteed to contain zeros. Hence we only have to handle the existing "beyond EOF" case and don't need access to the buffers on the page. Hence it remains largely unchanged. Note that xfs_getbmap() can still trip over delalloc blocks beyond EOF that are left there by speculative delayed allocation. Hence this bug fix does not solve all known issues with bmap vs delalloc, but it does fix all the the known accidental occurances of the problem. Signed-off-by:Dave Chinner <david@fromorbit.com> Signed-off-by:
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Dave Chinner authored
xfs_is_delayed_page() checks to see if a page has buffers matching the given IO type passed in. It does so by walking the buffer heads on the page and checking if the state flags match the IO type. However, the "acceptable" variable that is calculated is overwritten every time a new buffer is checked. Hence if the first buffer on the page is of the right type, this state is lost if the second buffer is not of the correct type. This means that xfs_aops_discard_page() may not discard delalloc regions when it is supposed to, and xfs_convert_page() may not cluster IO as efficiently as possible. This problem only occurs on filesystems with a block size smaller than page size. Also, rename xfs_is_delayed_page() to xfs_check_page_type() to better describe what it is doing - it is not delalloc specific anymore. The problem was first noticed by Peter Watkins. Signed-off-by:
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Dave Chinner authored
Doing background CIL flushes adds significant latency to whatever async transaction that triggers it. To avoid blocking async transactions on things like waiting for log buffer IO to complete, move the CIL push off into a workqueue. By moving the push work into a workqueue, we remove all the latency that the commit adds from the foreground transaction commit path. This also means that single threaded workloads won't do the CIL push procssing, leaving them more CPU to do more async transactions. To do this, we need to keep track of the sequence number we have pushed work for. This avoids having many transaction commits attempting to schedule work for the same sequence, and ensures that we only ever have one push (background or forced) in progress at a time. It also means that we don't need to take the CIL lock in write mode to check for potential background push races, which reduces lock contention. To avoid potential issues with "smart" IO schedulers, don't use the workqueue for log force triggered flushes. Instead, do them directly so that the log IO is done directly by the process issuing the log force and so doesn't get stuck on IO elevator queue idling incorrectly delaying the log IO from the workqueue. Signed-off-by:
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Dave Chinner authored
xfs_trans_ail_delete_bulk() can be called from different contexts so if the item is not in the AIL we need different shutdown for each context. Pass in the shutdown method needed so the correct action can be taken. Signed-off-by:
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Christoph Hellwig authored
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Christoph Hellwig authored
Queue delwri buffers on a local on-stack list instead of a per-buftarg one, and write back the buffers per-process instead of by waking up xfsbufd. This is now easily doable given that we have very few places left that write delwri buffers: - log recovery: Only done at mount time, and already forcing out the buffers synchronously using xfs_flush_buftarg - quotacheck: Same story. - dquot reclaim: Writes out dirty dquots on the LRU under memory pressure. We might want to look into doing more of this via xfsaild, but it's already more optimal than the synchronous inode reclaim that writes each buffer synchronously. - xfsaild: This is the main beneficiary of the change. By keeping a local list of buffers to write we reduce latency of writing out buffers, and more importably we can remove all the delwri list promotions which were hitting the buffer cache hard under sustained metadata loads. The implementation is very straight forward - xfs_buf_delwri_queue now gets a new list_head pointer that it adds the delwri buffers to, and all callers need to eventually submit the list using xfs_buf_delwi_submit or xfs_buf_delwi_submit_nowait. Buffers that already are on a delwri list are skipped in xfs_buf_delwri_queue, assuming they already are on another delwri list. The biggest change to pass down the buffer list was done to the AIL pushing. Now that we operate on buffers the trylock, push and pushbuf log item methods are merged into a single push routine, which tries to lock the item, and if possible add the buffer that needs writeback to the buffer list. This leads to much simpler code than the previous split but requires the individual IOP_PUSH instances to unlock and reacquire the AIL around calls to blocking routines. Given that xfsailds now also handle writing out buffers, the conditions for log forcing and the sleep times needed some small changes. The most important one is that we consider an AIL busy as long we still have buffers to push, and the other one is that we do increment the pushed LSN for buffers that are under flushing at this moment, but still count them towards the stuck items for restart purposes. Without this we could hammer on stuck items without ever forcing the log and not make progress under heavy random delete workloads on fast flash storage devices. [ Dave Chinner: - rebase on previous patches. - improved comments for XBF_DELWRI_Q handling - fix XBF_ASYNC handling in queue submission (test 106 failure) - rename delwri submit function buffer list parameters for clarity - xfs_efd_item_push() should return XFS_ITEM_PINNED ] Signed-off-by:
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Christoph Hellwig authored
Instead of adding buffers to the delwri list as soon as they are logged, even if they can't be written until commited because they are pinned defer adding them to the delwri list until xfsaild pushes them. This makes the code more similar to other log items and prepares for writing buffers directly from xfsaild. The complication here is that we need to fail buffers that were added but not logged yet in xfs_buf_item_unpin, borrowing code from xfs_bioerror. Signed-off-by:
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Christoph Hellwig authored
Instead of writing the buffer directly from inside xfs_qm_dqflush return it to the caller and let the caller decide what to do with the buffer. Also remove the pincount check in xfs_qm_dqflush that all non-blocking callers already implement and the now unused flags parameter and the XFS_DQ_IS_DIRTY check that all callers already perform. [ Dave Chinner: fixed build error cause by missing '{'. ] Signed-off-by: -
Christoph Hellwig authored
Instead of writing the buffer directly from inside xfs_iflush return it to the caller and let the caller decide what to do with the buffer. Also remove the pincount check in xfs_iflush that all non-blocking callers already implement and the now unused flags parameter. Signed-off-by:
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Christoph Hellwig authored
We already flush dirty inodes throug the AIL regularly, there is no reason to have second thread compete with it and disturb the I/O pattern. We still do write inodes when doing a synchronous reclaim from the shrinker or during unmount for now. Signed-off-by:
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Christoph Hellwig authored
Now that we write back all metadata either synchronously or through the AIL we can simply implement metadata freezing in terms of emptying the AIL. The implementation for this is fairly simply and straight-forward: A new routine is added that asks the xfsaild to push the AIL to the end and waits for it to complete and send a wakeup. The routine will then loop if the AIL is not actually empty, and continue to do so until the AIL is compeltely empty. We keep an inode reclaim pass in the freeze process to avoid having memory pressure have to reclaim inodes that require dirtying the filesystem to be reclaimed after the freeze has completed. This means we can also treat unmount in the exact same way as freeze. As an upside we can now remove the radix tree based inode writeback and xfs_unmountfs_writesb. [ Dave Chinner: - Cleaned up commit message. - Added inode reclaim passes back into freeze. - Cleaned up wakeup mechanism to avoid the use of a new sleep counter variable. ] Signed-off-by:
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Christoph Hellwig authored
Provide a variant of xlog_assign_tail_lsn that has the AIL lock already held. By doing so we do an additional atomic_read + atomic_set under the lock, which comes down to two instructions. Switch xfs_trans_ail_update_bulk and xfs_trans_ail_delete_bulk to the new version to reduce the number of lock roundtrips, and prepare for a new addition that would require a third lock roundtrip in xfs_trans_ail_delete_bulk. This addition is also the reason for slightly rearranging the conditionals and relying on xfs_log_space_wake for checking that the filesystem has been shut down internally. Signed-off-by:
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Christoph Hellwig authored
If a filesystem has been forced shutdown we are never going to write inodes to disk, which means the inode items will stay in the AIL until we free the inode. Currently that is not a problem, but a pending change requires us to empty the AIL before shutting down the filesystem. In that case leaving the inode in the AIL is lethal. Make sure to remove the log item from the AIL to allow emptying the AIL on shutdown filesystems. Signed-off-by:
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Christoph Hellwig authored
If a filesystem has been forced shutdown we are never going to write dquots to disk, which means the dquot items will stay in the AIL forever. Currently that is not a problem, but a pending chance requires us to empty the AIL before shutting down the filesystem, in which case this behaviour is lethal. Make sure to remove the log item from the AIL to allow emptying the AIL on shutdown filesystems. Signed-off-by:
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Shaohua Li authored
Issuing a block device flush request in transaction context using GFP_KERNEL directly can cause deadlocks due to memory reclaim recursion. Use GFP_NOFS to avoid recursion from reclaim context. Signed-off-by:
Shaohua Li <shli@fusionio.com> Reviewed-by:
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