- 27 Jun, 2013 9 commits
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Dave Chinner authored
Define the log and space transaction sizes. Factor the current create log reservation macro into the two logical halves and reuse one half for the new icreate transactions. The icreate transaction is transparent to all the high level create code - the pre-calculated reservations will correctly set the reservations dependent on whether the filesystem supports the icreate transaction. Signed-off-by:
Dave Chinner <david@fromorbit.com> Reviewed-by:
Mark Tinguely <tinguely@sgi.com> Signed-off-by:
Ben Myers <bpm@sgi.com>
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Dave Chinner authored
Introduce the inode create log item type for logical inode create logging. Instead of logging the changes in buffers, pass the range to be initialised through the log by a new transaction type. This reduces the amount of log space required to record initialisation during allocation from about 128 bytes per inode to a small fixed amount per inode extent to be initialised. This requires a new log item type to track it through the log and the AIL. This is a relatively simple item - most callbacks are noops as this item has the same life cycle as the transaction. Signed-off-by:
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Dave Chinner authored
If we have a buffer that we have modified but we do not wish to physically log in a transaction (e.g. we've logged a logical change), we still need to ensure that transactional integrity is maintained. Hence we must not move the tail of the log past the transaction that the buffer is associated with before the buffer is written to disk. This means these special buffers still need to be included in the transaction and added to the AIL just like a normal buffer, but we do not want the modifications to the buffer written into the transaction. IOWs, what we want is an "ordered buffer" that maintains the same transactional life cycle as a physically logged buffer, just without the transcribing of the modifications to the log. Hence we need to flag the buffer as an "ordered buffer" to avoid including it in vector size calculations or formatting during the transaction. Once the transaction is committed, the buffer appears for all intents to be the same as a physically logged buffer as it transitions through the log and AIL. Relogging will also work just fine for such an ordered buffer - the logical transaction will be replayed before the subsequent modifications that relog the buffer, so everything will be reconstructed correctly by recovery. Signed-off-by:
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Dave Chinner authored
And "ordered log vector" is a log vector that is used for tracking a log item through the CIL and into the AIL as part of the log checkpointing. These ordered log vectors are special in that they are not written to to journal in any way, and are not accounted to the checkpoint being written. The reason for this behaviour is to allow operations to attach items to transactions and have them follow the normal transactional lifecycle without actually having to write them to the journal. This allows logging of items that track high level logical changes and writing them to the log, while the physical items being modified pass through into the AIL and pin the tail of the log (and therefore the logical item in the log) until all the modified items are physically written to disk. IOWs, it allows us to write metadata without physically logging every individual change but still maintain the full transactional integrity guarantees we currently have w.r.t. crash recovery. This change modifies some of the CIL item insertion loops, as ordered log vectors introduce some new constraints as they don't track any data. One advantage of this change is that it combines two log vector chain walks into a single pass, so there is less overhead in the transaction commit pass as well. It also kills some unused code in the log vector walk loop when committing the CIL. Signed-off-by:
Dave Chinner <dchinner@redhat.com> Reviewed-by:
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Dave Chinner authored
Long ago, bulkstat used to read inodes directly from the backing buffer for speed. This had the unfortunate problem of being cache incoherent with unlinks, and so xfs_ifree() had to mark the inode as free directly in the backing buffer. bulkstat was changed some time ago to use inode cache coherent lookups, and so will never see unlinked inodes in it's lookups. Hence xfs_ifree() does not need to touch the inode backing buffer anymore. Signed-off-by:
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Dave Chinner authored
When we are allocating a new inode, we read the inode cluster off disk to increment the generation number. We are already using a random generation number for newly allocated inodes, so if we are not using the ikeep mode, we can just generate a new generation number when we initialise the newly allocated inode. This avoids the need for reading the inode buffer during inode creation. This will speed up allocation of inodes in cold, partially allocated clusters as they will no longer need to be read from disk during allocation. It will also reduce the CPU overhead of inode allocation by not having the process the buffer read, even on cache hits. Signed-off-by:
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Dave Chinner authored
Dedicated small file workloads have been seeing significant free space fragmentation causing premature inode allocation failure when large inode sizes are in use. A particular test case showed that a workload that runs to a real ENOSPC on 256 byte inodes would fail inode allocation with ENOSPC about about 80% full with 512 byte inodes, and at about 50% full with 1024 byte inodes. The same workload, when run with -o allocsize=4096 on 1024 byte inodes would run to being 100% full before giving ENOSPC. That is, no freespace fragmentation at all. The issue was caused by the specific IO pattern the application had - the framework it was using did not support direct IO, and so it was emulating it by using fadvise(DONT_NEED). The result was that the data was getting written back before the speculative prealloc had been trimmed from memory by the close(), and so small single block files were being allocated with 2 blocks, and then having one truncated away. The result was lots of small 4k free space extents, and hence each new 8k allocation would take another 8k from contiguous free space and turn it into 4k of allocated space and 4k of free space. Hence inode allocation, which requires contiguous, aligned allocation of 16k (256 byte inodes), 32k (512 byte inodes) or 64k (1024 byte inodes) can fail to find sufficiently large freespace and hence fail while there is still lots of free space available. There's a simple fix for this, and one that has precendence in the allocator code already - don't do speculative allocation unless the size of the file is larger than a certain size. In this case, that size is the minimum default preallocation size: mp->m_writeio_blocks. And to keep with the concept of being nice to people when the files are still relatively small, cap the prealloc to mp->m_writeio_blocks until the file goes over a stripe unit is size, at which point we'll fall back to the current behaviour based on the last extent size. This will effectively turn off speculative prealloc for very small files, keep preallocation low for small files, and behave as it currently does for any file larger than a stripe unit. This completely avoids the freespace fragmentation problem this particular IO pattern was causing. Signed-off-by:
Brian Foster <bfoster@redhat.com> Reviewed-by:
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Dave Chinner authored
Similar to bulkstat inode chunk readahead, we need to plug directory data buffer readahead during getdents to ensure that we can merge adjacent readahead requests and sort out of order requests optimally before they are dispatched. This improves the readahead efficiency and reduces the IO load it generates as the IO patterns are significantly better for both contiguous and fragmented directories. Signed-off-by:
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Dave Chinner authored
I was running some tests on bulkstat on CRC enabled filesystems when I noticed that all the IO being issued was 8k in size, regardless of the fact taht we are issuing sequential 8k buffers for inodes clusters. The IO size should be 16k for 256 byte inodes, and 32k for 512 byte inodes, but this wasn't happening. blktrace showed that there was an explict plug and unplug happening around each readahead IO from _xfs_buf_ioapply, and the unplug was causing the IO to be issued immediately. Hence no opportunity was being given to the elevator to merge adjacent readahead requests and dispatch them as a single IO. Add plugging around the inode chunk readahead dispatch loop in bulkstat to ensure that we don't unplug the queue between adjacent inode buffer readahead IOs and so we get fewer, larger IO requests hitting the storage subsystem for bulkstat. Signed-off-by:
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- 26 Jun, 2013 2 commits
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Jie Liu authored
Remove dead function prototype xfs_sync_inode_grab() from xfs_icache.h. Signed-off-by:
Jie Liu <jeff.liu@oracle.com> Reviewed-by:
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Jie Liu authored
This patch clean out the left function variable as it is useless to xfs_ialloc_get_rec(). Signed-off-by:
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- 20 Jun, 2013 1 commit
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Eric Sandeen authored
xfs_swap_extents_check_format() contains checks to make sure that original and the temporary files during defrag are compatible; Gabriel VLASIU ran into a case where xfs_fsr returned EINVAL because the tests found the btree root to be of size 120, while the fork offset was only 104; IOW, they overlapped. However, this is just due to an error in the xfs_swap_extents_check_format() tests, because it is checking the in-memory btree root size against the on-disk fork offset. We should be checking the on-disk sizes in both cases. This patch adds a new macro to calculate this size, and uses it in the tests. With this change, the filesystem image provided by Gabriel allows for proper file degragmentation. Reported-by:
Gabriel VLASIU <gabriel@vlasiu.net> Signed-off-by:
Eric Sandeen <sandeen@redhat.com> Reviewed-by:
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- 19 Jun, 2013 4 commits
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Jie Liu authored
XFS_MOUNT_RETERR is going to be set at xfs_parseargs() if mp->m_dalign is enabled, so any time we enter "if (mp->m_dalign)" branch in xfs_update_alignment(), XFS_MOUNT_RETERR is set and so we always be emitting a warning and returning an error. Hence, we can remove it and get rid of a couple of redundant check up against it at xfs_upate_alignment(). Thanks Dave Chinner for the suggestions of simplify the code in xfs_parseargs(). Signed-off-by:
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Jie Liu authored
Upstream commit 5b292ae3 xfs: make use of xfs_calc_buf_res() in xfs_trans.c Beginning from above commit, neither XFS_ALLOCFREE_LOG_RES() nor XFS_DIROP_LOG_RES() is used by those routines for calculating transaction space reservations, so it's safe to remove them now. Also, with a slightly update for the relevant comments to reflect the ideas of why those log count numbers should be. Signed-off-by:
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Jie Liu authored
For FIEMAP ioctl(2), if an extent is in delayed allocation state, we need to return the FIEMAP_EXTENT_UNKNOWN flag except the FIEMAP_EXTENT_DELALLOC because its data location is unknown. Signed-off-by:
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Mark Tinguely authored
Adding an extended attribute to a symbolic link can force that link to an remote extent. xfs_inactive() incorrectly assumes that any symbolic link small enough to be in the inode core is incore, resulting in the remote extent to not be removed. xfs_ifree() will assert on presence of this leaked remote extent. Signed-off-by:
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- 17 Jun, 2013 4 commits
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Jeff Liu authored
Remove struct xfs_chash from struct xfs_mount as there is no user of it nowadays. Signed-off-by:
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Jie Liu authored
As per the mount man page, sunit and swidth can be changed via mount options. For XFS, on the face of it, those options seems works if the specified alignments is properly, e.g. # mount -o sunit=4096,swidth=8192 /dev/sdb1 /mnt # mount | grep sdb1 /dev/sdb1 on /mnt type xfs (rw,sunit=4096,swidth=8192) However, neither sunit nor swidth is shown from the xfs_info output. # xfs_info /mnt meta-data=/dev/sdb1 isize=256 agcount=4, agsize=262144 blks = sectsz=512 attr=2 data = bsize=4096 blocks=1048576, imaxpct=25 = sunit=0 swidth=0 blks ^^^^^^^^^^^^^^^^^^^^^^^^^^ naming =version 2 bsize=4096 ascii-ci=0 log =internal bsize=4096 blocks=2560, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 The reason is that the alignment can only be changed if the relevant super block is already configured with alignments, otherwise, the given value is silently ignored. With this fix, the attempt to mount a storage without strip alignment setup on a super block will get an error with a warning in syslog to indicate the true cause, e.g. # mount -o sunit=4096,swidth=8192 /dev/sdb1 /mnt mount: wrong fs type, bad option, bad superblock on /dev/sdb1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so ....... XFS (sdb1): cannot change alignment: superblock does not support data alignment Signed-off-by: -
Jie Liu authored
Commit eab4e633 "xfs: uncached buffer reads need to return an error". Remove redundant error variable, using the function level error variable to store bp->b_error instead. Signed-off-by:
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Joe Perches authored
This typedef is unnecessary and should just be removed. Signed-off-by:
Joe Perches <joe@perches.com> Acked-by:
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- 14 Jun, 2013 1 commit
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Dave Chinner authored
Unfortunately, we cannot guarantee that items logged multiple times and replayed by log recovery do not take objects back in time. When they are taken back in time, the go into an intermediate state which is corrupt, and hence verification that occurs on this intermediate state causes log recovery to abort with a corruption shutdown. Instead of causing a shutdown and unmountable filesystem, don't verify post-recovery items before they are written to disk. This is less than optimal, but there is no way to detect this issue for non-CRC filesystems If log recovery successfully completes, this will be undone and the object will be consistent by subsequent transactions that are replayed, so in most cases we don't need to take drastic action. For CRC enabled filesystems, leave the verifiers in place - we need to call them to recalculate the CRCs on the objects anyway. This recovery problem can be solved for such filesystems - we have a LSN stamped in all metadata at writeback time that we can to determine whether the item should be replayed or not. This is a separate piece of work, so is not addressed by this patch. Signed-off-by:
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- 13 Jun, 2013 2 commits
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Dave Chinner authored
For CRC enabled filesystems, the BMBT is rooted in an inode, so it passes through a different code path on root splits than the freespace and inode btrees. This is much less traversed by xfstests than the other trees. When testing on a 1k block size filesystem, I've been seeing ASSERT failures in generic/234 like: XFS: Assertion failed: cur->bc_btnum != XFS_BTNUM_BMAP || cur->bc_private.b.allocated == 0, file: fs/xfs/xfs_btree.c, line: 317 which are generally preceded by a lblock check failure. I noticed this in the bmbt stats: $ pminfo -f xfs.btree.block_map xfs.btree.block_map.lookup value 39135 xfs.btree.block_map.compare value 268432 xfs.btree.block_map.insrec value 15786 xfs.btree.block_map.delrec value 13884 xfs.btree.block_map.newroot value 2 xfs.btree.block_map.killroot value 0 ..... Very little coverage of root splits and merges. Indeed, on a 4k filesystem, block_map.newroot and block_map.killroot are both zero. i.e. the code is not exercised at all, and it's the only generic btree infrastructure operation that is not exercised by a default run of xfstests. Turns out that on a 1k filesystem, generic/234 accounts for one of those two root splits, and that is somewhat of a smoking gun. In fact, it's the same problem we saw in the directory/attr code where headers are memcpy()d from one block to another without updating the self describing metadata. Simple fix - when copying the header out of the root block, make sure the block number is updated correctly. Signed-off-by: -
Dave Chinner authored
Michael L. Semon has been testing CRC patches on a 32 bit system and been seeing assert failures in the directory code from xfs/080. Thanks to Michael's heroic efforts with printk debugging, we found that the problem was that the last free space being left in the directory structure was too small to fit a unused tag structure and it was being corrupted and attempting to log a region out of bounds. Hence the assert failure looked something like: ..... #5 calling xfs_dir2_data_log_unused() 36 32 #1 4092 4095 4096 #2 8182 8183 4096 XFS: Assertion failed: first <= last && last < BBTOB(bp->b_length), file: fs/xfs/xfs_trans_buf.c, line: 568 Where #1 showed the first region of the dup being logged (i.e. the last 4 bytes of a directory buffer) and #2 shows the corrupt values being calculated from the length of the dup entry which overflowed the size of the buffer. It turns out that the problem was not in the logging code, nor in the freespace handling code. It is an initial condition bug that only shows up on 32 bit systems. When a new buffer is initialised, where's the freespace that is set up: [ 172.316249] calling xfs_dir2_leaf_addname() from xfs_dir_createname() [ 172.316346] #9 calling xfs_dir2_data_log_unused() [ 172.316351] #1 calling xfs_trans_log_buf() 60 63 4096 [ 172.316353] #2 calling xfs_trans_log_buf() 4094 4095 4096 Note the offset of the first region being logged? It's 60 bytes into the buffer. Once I saw that, I pretty much knew that the bug was going to be caused by this. Essentially, all direct entries are rounded to 8 bytes in length, and all entries start with an 8 byte alignment. This means that we can decode inplace as variables are naturally aligned. With the directory data supposedly starting on a 8 byte boundary, and all entries padded to 8 bytes, the minimum freespace in a directory block is supposed to be 8 bytes, which is large enough to fit a unused data entry structure (6 bytes in size). The fact we only have 4 bytes of free space indicates a directory data block alignment problem. And what do you know - there's an implicit hole in the directory data block header for the CRC format, which means the header is 60 byte on 32 bit intel systems and 64 bytes on 64 bit systems. Needs padding. And while looking at the structures, I found the same problem in the attr leaf header. Fix them both. Note that this only affects 32 bit systems with CRCs enabled. Everything else is just fine. Note that CRC enabled filesystems created before this fix on such systems will not be readable with this fix applied. Reported-by:
Michael L. Semon <mlsemon35@gmail.com> Debugged-by:
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- 05 Jun, 2013 4 commits
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Dave Chinner authored
The limit of 25 ACL entries is arbitrary, but baked into the on-disk format. For version 5 superblocks, increase it to the maximum nuber of ACLs that can fit into a single xattr. Signed-off-by:
Mark Tinguely <tinuguely@sgi.com> Signed-off-by:
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Dave Chinner authored
attr2 format is always enabled for v5 superblock filesystems, so the mount options to enable or disable it need to be cause mount errors. Signed-off-by:
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Dave Chinner authored
The inode unlinked list manipulations operate directly on the inode buffer, and so bypass the inode CRC calculation mechanisms. Hence an inode on the unlinked list has an invalid CRC. Fix this by recalculating the CRC whenever we modify an unlinked list pointer in an inode, ncluding during log recovery. This is trivial to do and results in unlinked list operations always leaving a consistent inode in the buffer. Signed-off-by:
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Dave Chinner authored
There are several constraints that inode allocation and unlink logging impose on log recovery. These all stem from the fact that inode alloc/unlink are logged in buffers, but all other inode changes are logged in inode items. Hence there are ordering constraints that recovery must follow to ensure the correct result occurs. As it turns out, this ordering has been working mostly by chance than good management. The existing code moves all buffers except cancelled buffers to the head of the list, and everything else to the tail of the list. The problem with this is that is interleaves inode items with the buffer cancellation items, and hence whether the inode item in an cancelled buffer gets replayed is essentially left to chance. Further, this ordering causes problems for log recovery when inode CRCs are enabled. It typically replays the inode unlink buffer long before it replays the inode core changes, and so the CRC recorded in an unlink buffer is going to be invalid and hence any attempt to validate the inode in the buffer is going to fail. Hence we really need to enforce the ordering that the inode alloc/unlink code has expected log recovery to have since inode chunk de-allocation was introduced back in 2003... Signed-off-by:
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- 04 Jun, 2013 2 commits
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Dave Chinner authored
When invalidating an attribute leaf block block, there might be remote attributes that it points to. With the recent rework of the remote attribute format, we have to make sure we calculate the length of the attribute correctly. We aren't doing that in xfs_attr3_leaf_inactive(), so fix it. Signed-off-by:
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Dave Chinner authored
Calculating dquot CRCs when the backing buffer is written back just doesn't work reliably. There are several places which manipulate dquots directly in the buffers, and they don't calculate CRCs appropriately, nor do they always set the buffer up to calculate CRCs appropriately. Firstly, if we log a dquot buffer (e.g. during allocation) it gets logged without valid CRC, and so on recovery we end up with a dquot that is not valid. Secondly, if we recover/repair a dquot, we don't have a verifier attached to the buffer and hence CRCs are not calculated on the way down to disk. Thirdly, calculating the CRC after we've changed the contents means that if we re-read the dquot from the buffer, we cannot verify the contents of the dquot are valid, as the CRC is invalid. So, to avoid all the dquot CRC errors that are being detected by the read verifier, change to using the same model as for inodes. That is, dquot CRCs are calculated and written to the backing buffer at the time the dquot is flushed to the backing buffer. If we modify the dquot directly in the backing buffer, calculate the CRC immediately after the modification is complete. Hence the dquot in the on-disk buffer should always have a valid CRC. Signed-off-by:
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- 30 May, 2013 7 commits
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Dave Chinner authored
When the directory freespace index grows to a second block (2017 4k data blocks in the directory), the initialisation of the second new block header goes wrong. The write verifier fires a corruption error indicating that the block number in the header is zero. This was being tripped by xfs/110. The problem is that the initialisation of the new block is done just fine in xfs_dir3_free_get_buf(), but the caller then users a dirv2 structure to zero on-disk header fields that xfs_dir3_free_get_buf() has already zeroed. These lined up with the block number in the dir v3 header format. While looking at this, I noticed that the struct xfs_dir3_free_hdr() had 4 bytes of padding in it that wasn't defined as padding or being zeroed by the initialisation. Add a pad field declaration and fully zero the on disk and in-core headers in xfs_dir3_free_get_buf() so that this is never an issue in the future. Note that this doesn't change the on-disk layout, just makes the 32 bits of padding in the layout explicit. Signed-off-by:
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Dave Chinner authored
XFS has failed to kill suid/sgid bits correctly when truncating files of non-zero size since commit c4ed4243 ("xfs: split xfs_setattr") introduced in the 3.1 kernel. Fix it. Fix it. cc: stable kernel <stable@vger.kernel.org> Signed-off-by:
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Dave Chinner authored
Currently userspace has no way of determining that a filesystem is CRC enabled. Add a flag to the XFS_IOC_FSGEOMETRY ioctl output to indicate that the filesystem has v5 superblock support enabled. This will allow xfs_info to correctly report the state of the filesystem. Signed-off-by:
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Dave Chinner authored
Currently, swapping extents from one inode to another is a simple act of switching data and attribute forks from one inode to another. This, unfortunately in no longer so simple with CRC enabled filesystems as there is owner information embedded into the BMBT blocks that are swapped between inodes. Hence swapping the forks between inodes results in the inodes having mapping blocks that point to the wrong owner and hence are considered corrupt. To fix this we need an extent tree block or record based swap algorithm so that the BMBT block owner information can be updated atomically in the swap transaction. This is a significant piece of new work, so for the moment simply don't allow swap extent operations to succeed on CRC enabled filesystems. Signed-off-by:
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Dave Chinner authored
A long time ago in a galaxy far away.... .. the was a commit made to fix some ilinux specific "fragmented buffer" log recovery problem: http://oss.sgi.com/cgi-bin/gitweb.cgi?p=archive/xfs-import.git;a=commitdiff;h=b29c0bece51da72fb3ff3b61391a391ea54e1603 That problem occurred when a contiguous dirty region of a buffer was split across across two pages of an unmapped buffer. It's been a long time since that has been done in XFS, and the changes to log the entire inode buffers for CRC enabled filesystems has re-introduced that corner case. And, of course, it turns out that the above commit didn't actually fix anything - it just ensured that log recovery is guaranteed to fail when this situation occurs. And now for the gory details. xfstest xfs/085 is failing with this assert: XFS (vdb): bad number of regions (0) in inode log format XFS: Assertion failed: 0, file: fs/xfs/xfs_log_recover.c, line: 1583 Largely undocumented factoid #1: Log recovery depends on all log buffer format items starting with this format: struct foo_log_format { __uint16_t type; __uint16_t size; .... As recoery uses the size field and assumptions about 32 bit alignment in decoding format items. So don't pay much attention to the fact log recovery thinks that it decoding an inode log format item - it just uses them to determine what the size of the item is. But why would it see a log format item with a zero size? Well, luckily enough xfs_logprint uses the same code and gives the same error, so with a bit of gdb magic, it turns out that it isn't a log format that is being decoded. What logprint tells us is this: Oper (130): tid: a0375e1a len: 28 clientid: TRANS flags: none BUF: #regs: 2 start blkno: 144 (0x90) len: 16 bmap size: 2 flags: 0x4000 Oper (131): tid: a0375e1a len: 4096 clientid: TRANS flags: none BUF DATA ---------------------------------------------------------------------------- Oper (132): tid: a0375e1a len: 4096 clientid: TRANS flags: none xfs_logprint: unknown log operation type (4e49) ********************************************************************** * ERROR: data block=2 * ********************************************************************** That we've got a buffer format item (oper 130) that has two regions; the format item itself and one dirty region. The subsequent region after the buffer format item and it's data is them what we are tripping over, and the first bytes of it at an inode magic number. Not a log opheader like there is supposed to be. That means there's a problem with the buffer format item. It's dirty data region is 4096 bytes, and it contains - you guessed it - initialised inodes. But inode buffers are 8k, not 4k, and we log them in their entirety. So something is wrong here. The buffer format item contains: (gdb) p /x *(struct xfs_buf_log_format *)in_f $22 = {blf_type = 0x123c, blf_size = 0x2, blf_flags = 0x4000, blf_len = 0x10, blf_blkno = 0x90, blf_map_size = 0x2, blf_data_map = {0xffffffff, 0xffffffff, .... }} Two regions, and a signle dirty contiguous region of 64 bits. 64 * 128 = 8k, so this should be followed by a single 8k region of data. And the blf_flags tell us that the type of buffer is a XFS_BLFT_DINO_BUF. It contains inodes. And because it doesn't have the XFS_BLF_INODE_BUF flag set, that means it's an inode allocation buffer. So, it should be followed by 8k of inode data. But we know that the next region has a header of: (gdb) p /x *ohead $25 = {oh_tid = 0x1a5e37a0, oh_len = 0x100000, oh_clientid = 0x69, oh_flags = 0x0, oh_res2 = 0x0} and so be32_to_cpu(oh_len) = 0x1000 = 4096 bytes. It's simply not long enough to hold all the logged data. There must be another region. There is - there's a following opheader for another 4k of data that contains the other half of the inode cluster data - the one we assert fail on because it's not a log format header. So why is the second part of the data not being accounted to the correct buffer log format structure? It took a little more work with gdb to work out that the buffer log format structure was both expecting it to be there but hadn't accounted for it. It was at that point I went to the kernel code, as clearly this wasn't a bug in xfs_logprint and the kernel was writing bad stuff to the log. First port of call was the buffer item formatting code, and the discontiguous memory/contiguous dirty region handling code immediately stood out. I've wondered for a long time why the code had this comment in it: vecp->i_addr = xfs_buf_offset(bp, buffer_offset); vecp->i_len = nbits * XFS_BLF_CHUNK; vecp->i_type = XLOG_REG_TYPE_BCHUNK; /* * You would think we need to bump the nvecs here too, but we do not * this number is used by recovery, and it gets confused by the boundary * split here * nvecs++; */ vecp++; And it didn't account for the extra vector pointer. The case being handled here is that a contiguous dirty region lies across a boundary that cannot be memcpy()d across, and so has to be split into two separate operations for xlog_write() to perform. What this code assumes is that what is written to the log is two consecutive blocks of data that are accounted in the buf log format item as the same contiguous dirty region and so will get decoded as such by the log recovery code. The thing is, xlog_write() knows nothing about this, and so just does it's normal thing of adding an opheader for each vector. That means the 8k region gets written to the log as two separate regions of 4k each, but because nvecs has not been incremented, the buf log format item accounts for only one of them. Hence when we come to log recovery, we process the first 4k region and then expect to come across a new item that starts with a log format structure of some kind that tells us whenteh next data is going to be. Instead, we hit raw buffer data and things go bad real quick. So, the commit from 2002 that commented out nvecs++ is just plain wrong. It breaks log recovery completely, and it would seem the only reason this hasn't been since then is that we don't log large contigous regions of multi-page unmapped buffers very often. Never would be a closer estimate, at least until the CRC code came along.... So, lets fix that by restoring the nvecs accounting for the extra region when we hit this case..... .... and there's the problemin log recovery it is apparently working around: XFS: Assertion failed: i == item->ri_total, file: fs/xfs/xfs_log_recover.c, line: 2135 Yup, xlog_recover_do_reg_buffer() doesn't handle contigous dirty regions being broken up into multiple regions by the log formatting code. That's an easy fix, though - if the number of contiguous dirty bits exceeds the length of the region being copied out of the log, only account for the number of dirty bits that region covers, and then loop again and copy more from the next region. It's a 2 line fix. Now xfstests xfs/085 passes, we have one less piece of mystery code, and one more important piece of knowledge about how to structure new log format items.. Signed-off-by:
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Dave Chinner authored
When CRCs are enabled, the number of blocks needed to hold a remote symlink on a 1k block size filesystem may be 2 instead of 1. The transaction reservation for the allocated blocks was not taking this into account and only allocating one block. Hence when trying to read or invalidate such symlinks, we are mapping a hole where there should be a block and things go bad at that point. Fix the reservation to use the correct block count, clean up the block count calculation similar to the remote attribute calculation, and add a debug guard to detect when we don't write the entire symlink to disk. Signed-off-by:
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Dave Chinner authored
We write the superblock every 30s or so which results in the verifier being called. Right now that results in this output every 30s: XFS (vda): Version 5 superblock detected. This kernel has EXPERIMENTAL support enabled! Use of these features in this kernel is at your own risk! And spamming the logs. We don't need to check for whether we support v5 superblocks or whether there are feature bits we don't support set as these are only relevant when we first mount the filesytem. i.e. on superblock read. Hence for the write verification we can just skip all the checks (and hence verbose output) altogether. Signed-off-by:
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- 23 May, 2013 4 commits
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Dave Chinner authored
Note: this changes the on-disk remote attribute format. I assert that this is OK to do as CRCs are marked experimental and the first kernel it is included in has not yet reached release yet. Further, the userspace utilities are still evolving and so anyone using this stuff right now is a developer or tester using volatile filesystems for testing this feature. Hence changing the format right now to save longer term pain is the right thing to do. The fundamental change is to move from a header per extent in the attribute to a header per filesytem block in the attribute. This means there are more header blocks and the parsing of the attribute data is slightly more complex, but it has the advantage that we always know the size of the attribute on disk based on the length of the data it contains. This is where the header-per-extent method has problems. We don't know the size of the attribute on disk without first knowing how many extents are used to hold it. And we can't tell from a mapping lookup, either, because remote attributes can be allocated contiguously with other attribute blocks and so there is no obvious way of determining the actual size of the atribute on disk short of walking and mapping buffers. The problem with this approach is that if we map a buffer incorrectly (e.g. we make the last buffer for the attribute data too long), we then get buffer cache lookup failure when we map it correctly. i.e. we get a size mismatch on lookup. This is not necessarily fatal, but it's a cache coherency problem that can lead to returning the wrong data to userspace or writing the wrong data to disk. And debug kernels will assert fail if this occurs. I found lots of niggly little problems trying to fix this issue on a 4k block size filesystem, finally getting it to pass with lots of fixes. The thing is, 1024 byte filesystems still failed, and it was getting really complex handling all the corner cases that were showing up. And there were clearly more that I hadn't found yet. It is complex, fragile code, and if we don't fix it now, it will be complex, fragile code forever more. Hence the simple fix is to add a header to each filesystem block. This gives us the same relationship between the attribute data length and the number of blocks on disk as we have without CRCs - it's a linear mapping and doesn't require us to guess anything. It is simple to implement, too - the remote block count calculated at lookup time can be used by the remote attribute set/get/remove code without modification for both CRC and non-CRC filesystems. The world becomes sane again. Because the copy-in and copy-out now need to iterate over each filesystem block, I moved them into helper functions so we separate the block mapping and buffer manupulations from the attribute data and CRC header manipulations. The code becomes much clearer as a result, and it is a lot easier to understand and debug. It also appears to be much more robust - once it worked on 4k block size filesystems, it has worked without failure on 1k block size filesystems, too. Signed-off-by:
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Dave Chinner authored
xfs_attr3_leaf_compact() uses a temporary buffer for compacting the the entries in a leaf. It copies the the original buffer into the temporary buffer, then zeros the original buffer completely. It then copies the entries back into the original buffer. However, the original buffer has not been correctly initialised, and so the movement of the entries goes horribly wrong. Make sure the zeroed destination buffer is fully initialised, and once we've set up the destination incore header appropriately, write is back to the buffer before starting to move entries around. While debugging this, the _d/_s prefixes weren't sufficient to remind me what buffer was what, so rename then all _src/_dst. Signed-off-by:
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Dave Chinner authored
xfs_attr3_leaf_unbalance() uses a temporary buffer for recombining the entries in two leaves when the destination leaf requires compaction. The temporary buffer ends up being copied back over the original destination buffer, so the header in the temporary buffer needs to contain all the information that is in the destination buffer. To make sure the temporary buffer is fully initialised, once we've set up the temporary incore header appropriately, write is back to the temporary buffer before starting to move entries around. Signed-off-by:
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Dave Chinner authored
If we don't map the buffers correctly (same as for get/set operations) then the incore buffer lookup will fail. If a block number matches but a length is wrong, then debug kernels will ASSERT fail in _xfs_buf_find() due to the length mismatch. Ensure that we map the buffers correctly by basing the length of the buffer on the attribute data length rather than the remote block count. Signed-off-by:
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