- 24 May, 2010 8 commits
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Dave Chinner authored
Document the design of the delayed logging implementation. This includes assumptions made, dead ends followed, the reasoning behind the structuring of the code, the layout of various structures, how things fit together, traps and pit-falls avoided, etc. This is all too much to document in the code itself, so do it in a separate file. Signed-off-by:
Dave Chinner <dchinner@redhat.com> Signed-off-by:
Alex Elder <aelder@sgi.com>
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Dave Chinner authored
When we free a metadata extent, we record it in the per-AG busy extent array so that it is not re-used before the freeing transaction hits the disk. This array is fixed size, so when it overflows we make further allocation transactions synchronous because we cannot track more freed extents until those transactions hit the disk and are completed. Under heavy mixed allocation and freeing workloads with large log buffers, we can overflow this array quite easily. Further, the array is sparsely populated, which means that inserts need to search for a free slot, and array searches often have to search many more slots that are actually used to check all the busy extents. Quite inefficient, really. To enable this aspect of extent freeing to scale better, we need a structure that can grow dynamically. While in other areas of XFS we have used radix trees, the extents being freed are at random locations on disk so are better suited to being indexed by an rbtree. So, use a per-AG rbtree indexed by block number to track busy extents. This incures a memory allocation when marking an extent busy, but should not occur too often in low memory situations. This should scale to an arbitrary number of extents so should not be a limitation for features such as in-memory aggregation of transactions. However, there are still situations where we can't avoid allocating busy extents (such as allocation from the AGFL). To minimise the overhead of such occurences, we need to avoid doing a synchronous log force while holding the AGF locked to ensure that the previous transactions are safely on disk before we use the extent. We can do this by marking the transaction doing the allocation as synchronous rather issuing a log force. Because of the locking involved and the ordering of transactions, the synchronous transaction provides the same guarantees as a synchronous log force because it ensures that all the prior transactions are already on disk when the synchronous transaction hits the disk. i.e. it preserves the free->allocate order of the extent correctly in recovery. By doing this, we avoid holding the AGF locked while log writes are in progress, hence reducing the length of time the lock is held and therefore we increase the rate at which we can allocate and free from the allocation group, thereby increasing overall throughput. The only problem with this approach is that when a metadata buffer is marked stale (e.g. a directory block is removed), then buffer remains pinned and locked until the log goes to disk. The issue here is that if that stale buffer is reallocated in a subsequent transaction, the attempt to lock that buffer in the transaction will hang waiting the log to go to disk to unlock and unpin the buffer. Hence if someone tries to lock a pinned, stale, locked buffer we need to push on the log to get it unlocked ASAP. Effectively we are trading off a guaranteed log force for a much less common trigger for log force to occur. Ideally we should not reallocate busy extents. That is a much more complex fix to the problem as it involves direct intervention in the allocation btree searches in many places. This is left to a future set of modifications. Finally, now that we track busy extents in allocated memory, we don't need the descriptors in the transaction structure to point to them. We can replace the complex busy chunk infrastructure with a simple linked list of busy extents. This allows us to remove a large chunk of code, making the overall change a net reduction in code size. Signed-off-by:
Dave Chinner <david@fromorbit.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
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Dave Chinner authored
The ticket ID is needed to uniquely identify transactions when doing busy extent matching. Delayed logging changes the lifecycle of busy extents with respect to the transaction structure lifecycle. Hence we can no longer use the transaction structure as a means of determining the owner of the busy extent as it may be freed and reused while the busy extent is still active. This commit provides the infrastructure to access the xlog_tid_t held in the ticket from a transaction handle. This avoids the need for callers to peek into the transaction and log structures to find this out. Signed-off-by:
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Dave Chinner authored
Push the error message output when a ticket overrun is detected into the ticket printing functions. Also remove the debug version of the code as the production version will still panic just as effectively on a debug kernel via the panic mask being set. Signed-off-by:
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Dave Chinner authored
Clean up the buffer log format (XFS_BLI_*) flags because they have a polluted namespace. They XFS_BLI_ prefix is used for both in-memory and on-disk flag feilds, but have overlapping values for different flags. Rename the buffer log format flags to use the XFS_BLF_* prefix to avoid confusing them with the in-memory XFS_BLI_* prefixed flags. Signed-off-by:
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Dave Chinner authored
The buffer log item reference counts used to take referenceѕ for every transaction, similar to the pin counting. This is symmetric (like the pin/unpin) with respect to transaction completion, but with dleayed logging becomes assymetric as the pinning becomes assymetric w.r.t. transaction completion. To make both cases the same, allow the buffer pinning to take a reference to the buffer log item and always drop the reference the transaction has on it when being unlocked. This is balanced correctly because the unpin operation always drops a reference to the log item. Hence reference counting becomes symmetric w.r.t. item pinning as well as w.r.t active transactions and as a result the reference counting model remain consistent between normal and delayed logging. Signed-off-by:
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Dave Chinner authored
Delayed logging currently requires ticket allocation to succeed, so we need to be able to sleep on allocation. It also should not allow memory allocation to recurse into the filesystem. hence we need to pass allocation flags directing the type of allocation the caller requires. Signed-off-by:
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Dave Chinner authored
The transaction ID is written into the log as the unique identifier for transactions during recover. When duplicating a transaction, we reuse the log ticket, which means it has the same transaction ID as the previous transaction. Rather than regenerating a random transaction ID for the duplicated transaction, just add one to the current ID so that duplicated transaction can be easily spotted in the log and during recovery during problem diagnosis. Signed-off-by:
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- 19 May, 2010 32 commits
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Christoph Hellwig authored
And also drop a useless argument to xfs_iomap_write_direct. Signed-off-by:
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Christoph Hellwig authored
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Christoph Hellwig authored
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Christoph Hellwig authored
Rename all iomap_valid identifiers to imap_valid to fit the new world order, and clean up xfs_iomap_valid to convert the passed in offset to blocks instead of the imap values to bytes. Use the simpler inode->i_blkbits instead of the XFS macros for this. Signed-off-by:
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Christoph Hellwig authored
The IOMAP_ flags are now only used inside xfs_aops.c for extent probing and I/O completion tracking, so more them here, and rename them to IO_* as there's no mapping involved at all. Signed-off-by:
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Christoph Hellwig authored
Now that struct xfs_iomap contains exactly the same units as struct xfs_bmbt_irec we can just use the latter directly in the aops code. Replace the missing IOMAP_NEW flag with a new boolean output parameter to xfs_iomap. Signed-off-by:
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Christoph Hellwig authored
Report the iomap_bn field of struct xfs_iomap in terms of filesystem blocks instead of in terms of bytes. Shift the byte conversions into the caller, and replace the IOMAP_DELAY and IOMAP_HOLE flag checks with checks for HOLESTARTBLOCK and DELAYSTARTBLOCK. Signed-off-by:
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Christoph Hellwig authored
Report the iomap_offset and iomap_bsize fields of struct xfs_iomap in terms of fsblocks instead of in terms of disk blocks. Shift the byte conversions into the callers temporarily, but they will disappear or get cleaned up later. Signed-off-by:
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Christoph Hellwig authored
The iomap_delta field in struct xfs_iomap just contains the difference between the offset passed to xfs_iomap and the iomap_offset. Just calculate it in the only caller that cares. Signed-off-by:
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Christoph Hellwig authored
Instead of using the iomap_target field in struct xfs_iomap and the IOMAP_REALTIME flag just use the already existing xfs_find_bdev_for_inode helper. There's some fallout as we need to pass the inode in a few more places, which we also use to sanitize some calling conventions. Signed-off-by:
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Christoph Hellwig authored
We only call xfs_iomap for single mappings anyway, so remove all code dealing with multiple mappings from xfs_imap_to_bmap and add asserts that we never get results that we do not expect. Signed-off-by:
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Christoph Hellwig authored
We currenly have a routine xfs_trans_buf_item_match_all which checks if any log item in a transaction contains a given buffer, and a second one that only does this check for the first, embedded chunk of log items. We only use the second routine if we know we only have that log item chunk, so get rid of the limited routine and always use the more complete one. Also rename the old xfs_trans_buf_item_match_all to xfs_trans_buf_item_match and update various surrounding comments, and move the remaining xfs_trans_buf_item_match on top of the file to avoid a forward prototype. Signed-off-by:
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Tao Ma authored
According to Documentation/filesystems/fiemap.txt, If fm_extent_count is zero, then the fm_extents[] array is ignored (no extents will be returned), and the fm_mapped_extents count will hold the number of extents needed. But as the commit 97db39a1 has changed bmv_count to the caller's input buffer, this number query function can't work any more. As this commit is written to change bmv_count from MAXEXTNUM because of ENOMEM. This patch just try to set bm.bmv_count to something sane. Thanks to Dave Chinner <david@fromorbit.com> for the suggestion. Cc: Eric Sandeen <sandeen@redhat.com> Cc: Alex Elder <aelder@sgi.com> Reviewed-by:
Tao Ma <tao.ma@oracle.com>
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Alex Elder authored
There remains only one user of the l_sectbb_mask field in the log structure. Just kill it off and compute the mask where needed from the power-of-2 sector size. (Only update from last post is to accomodate the changes in the previous patch in the series.) Signed-off-by:
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Alex Elder authored
Change struct log so it keeps track of the size (in basic blocks) of a log sector in l_sectBBsize rather than the log-base-2 of that value (previously, l_sectbb_log). The name was chosen for consistency with the other fields in the structure that represent a number of basic blocks. (Updated so that a variable used in computing and verifying a log's sector size is named "log2_size". Also added the "BB" to the structure field name, based on feedback from Eric Sandeen. Also dropped some superfluous parentheses.) Signed-off-by:
Eric Sandeen <sandeen@sandeen.net>
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Christoph Hellwig authored
This can't be enabled through the build system and has been dead for ages. Note that the CRC patches add back log checksumming, but the code is quite different from the version removed here anyway. Signed-off-by:
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Christoph Hellwig authored
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Christoph Hellwig authored
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Christoph Hellwig authored
Access fields in m_quotainfo directly instead of hiding them behind the XFS_QI_* macros. Add local variables for the quotainfo pointer in places where we have lots of them. Signed-off-by:
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Christoph Hellwig authored
We need to wait for all pending direct I/O requests before taking care of metadata in fsync and write_inode. Signed-off-by:
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Andrea Gelmini authored
fs/xfs/linux-2.6/xfs_trace.c: xfs_attr_sf.h is included more than once. Signed-off-by:
Andrea Gelmini <andrea.gelmini@gelma.net> Signed-off-by:
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Alex Elder authored
Odds and ends in "xfs_log_recover.c". This patch just contains some minor things that didn't seem to warrant their own individual patches: - In xlog_bread_noalign(), drop an assertion that a pointer is non-null (the crash will tell us it was a bad pointer). - Add a more descriptive header comment for xlog_find_verify_cycle(). - Make a few additions to the comments in xlog_find_head(). Also rearrange some expressions in a few spots to produce the same result, but in a way that seems more clear what's being computed. (Updated in response to Dave's review comments. Note I did not split this patch like I said I would.) Signed-off-by:
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Alex Elder authored
In xlog_find_cycle_start() use a local variable for some repeated operations rather than constantly accessing the memory location whose address is passed in. (This version drops an assertion that a pointer is non-null.) Signed-off-by:
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Alex Elder authored
Rename a label used in xlog_find_head() that I thought was poorly chosen. Also combine two adjacent labels xlog_find_tail() into a single label, and give it a more generic name. (Now using Dave's suggested "validate_head" name for first label.) Signed-off-by:
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Christoph Hellwig authored
xfs_bwrite is used with the intention of synchronously writing out buffers, but currently it does not actually clear the async flag if that's left from previous writes but instead implements async behaviour if it finds it. Remove the code handling asynchronous writes as we've got rid of those entirely outside of the log and delwri buffers, and make sure that we clear the async and read flags before writing the buffer. Signed-off-by:
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Christoph Hellwig authored
All modifications to the superblock are done transactional through xfs_trans_log_buf, so there is no reason to initiate periodic asynchronous writeback. This only removes the superblock from the delwri list and will lead to sub-optimal I/O scheduling. Cut down xfs_sync_fsdata now that it's only used for synchronous superblock writes and move the log coverage checks into the two callers. Signed-off-by:
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Dave Chinner authored
The transaction ID that is written to the log for a transaction is currently set by taking the lower 32 bits of the memory address of the ticket structure. This is not guaranteed to be unique as tickets comes from a slab and slots can be reallocated immediately after being freed. As a result, there is no guarantee of uniqueness in the ticket ID value. Fix this by assigning a random number to the ticket ID field so that it is extremely unlikely that duplicates will occur and remove the possibility of transactions being mixed up during recovery due to duplicate IDs. Signed-off-by:
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Alex Elder authored
There are a number of places where a log sector size of 1 uses special case code. The round_up() and round_down() macros produce the correct result even when the log sector size is 1, and this eliminates the need for treating this as a special case. Signed-off-by:
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Alex Elder authored
Define a function that encapsulates checking the validity of a log block count. (Updated from previous version--no longer includes error reporting in the encapsulated validation function.) Signed-off-by:
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Alex Elder authored
XLOG_SECTOR_ROUNDUP_BBCOUNT() and XLOG_SECTOR_ROUNDDOWN_BLKNO() are now fairly simple macro translations. Just get rid of them in favor of the round_up() and round_down() macro calls they represent. Also, in spots in xlog_get_bp() and xlog_write_log_records(), round_up() was being called with value 1, which just evaluates to the macro's second argument; so just use that instead. In the latter case, make use of that value, as long as it's already been computed. Signed-off-by:
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Alex Elder authored
XLOG_SECTOR_ROUNDUP_BBCOUNT() is defined in "fs/xfs/xfs_log_recover.c" in an overly-complicated way. It is basically roundup(), but that is not at all clear from its definition. (Actually, there is another macro round_up() that applies for power-of-two-based masks which I'll be using here.) The operands in XLOG_SECTOR_ROUNDUP_BBCOUNT() are basically the block number (bbs) and the log sector basic block mask (log->l_sectbb_mask). I'll call them B and M for this discussion. The macro computes is value this way: M && (B & M) ? (B + M + 1) & ~M : B Put another way, we can break it into 3 cases: 1) ! M -> B # 0 mask, no effect 2) ! (B & M) -> B # sector aligned 3) M && (B & M) -> (B + M + 1) & ~M # round up otherwise The round_up() macro is cleverly defined using a value, v, and a power-of-2, p, and the result is the nearest multiple of p greater than or equal to v. Its value is computed something like this: ((v - 1) | (p - 1)) + 1 Let's consider using this in the context of the 3 cases above. When p = 2^0 = 1, the result boils down to ((v - 1) | 0) + 1, so it just translates any value v to itself. That handles case (1) above. When p = 2^n, n > 0, we know that (p - 1) will be a mask with all n bits 0..n-1 set. The condition in this case occurs when none of those mask bits is set in the value v provided. If that is the case, subtracting 1 from v will have 1's in all those lower bits (at least). Therefore, OR-ing the mask with that decremented value has no effect, so adding the 1 back again will just translate the v to itself. This handles case (2). Otherwise, the value v is greater than some multiple of p, and decrementing it will produce a result greater than or equal to that multiple. OR-ing in the mask will produce a value 1 less than the next multiple of p, so finally adding 1 back will result in the desired rounded-up value. This handles case (3). Hopefully this is convincing. While I was at it, I converted XLOG_SECTOR_ROUNDDOWN_BLKNO() to use the round_down() macro. Signed-off-by:
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Alex Elder authored
This fixes a bug in two places that I found by inspection. In xlog_find_verify_cycle() and xlog_write_log_records(), the code attempts to allocate a buffer to hold as many blocks as possible. It gives up if the number of blocks to be allocated gets too small. Right now it uses log->l_sectbb_log as that lower bound, but I'm sure it's supposed to be the actual log sector size instead. That is, the lower bound should be (1 << log->l_sectbb_log). Also define a simple macro xlog_sectbb(log) to represent the number of basic blocks in a sector for the given log. (No change from original submission; I have implemented Christoph's suggestion about storing l_sectsize rather than l_sectbb_log in a new, separate patch in this series.) Signed-off-by:
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