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* xfs: add xfs_trim_extentDarrick J. Wong2016-10-20
| | | | | | | | | | | | | | | | | | This helpers allows to trim an extent to a subset of it's original range while making sure the block numbers in it remain valid, In the future xfs_trim_extent and xfs_bmapi_trim_map should probably be merged in some form. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> [hch: split from a previous patch from Darrick, moved around and added support for "raw" delayed extents"] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* libxfs: v3 inodes are only valid on crc-enabled filesystemsRoger Willcocks2016-10-20
| | | | | | | | | | | | | | | | | | | | | xfs_repair was not detecting that version 3 inodes are invalid for for non-CRC filesystems. The result is specific inode corruptions go undetected and hence aren't repaired if only the version number is out of range. The core of the problem is that the XFS_DINODE_GOOD_VERSION() macro doesn't know that valid inode versions are dependent on a superblock version number. Fix this in libxfs, and propagate the new function out into the rest of xfsprogs to fix the issue. [Darrick: port to kernel from xfsprogs] Reported-by: Leslie Rhorer <lrhorer@mygrande.net> Signed-off-by: Roger Willcocks <roger@filmlight.ltd.uk> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* libxfs: clean up _calc_dquots_per_chunkDarrick J. Wong2016-10-20
| | | | | | | | | | | | | | The function xfs_calc_dquots_per_chunk takes a parameter in units of basic blocks. The kernel seems to get the units wrong, but userspace got 'fixed' by commenting out the unnecessary conversion. Fix both. cc: <stable@vger.kernel.org> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* xfs: remove pointless error goto in xfs_bmap_remap_allocEric Sandeen2016-10-20
| | | | | | | | | | | | | | | | The commit: f65306ea xfs: map an inode's offset to an exact physical block added a pointless error0: target; remove it. Addresses-Coverity-Id: 1373865 Signed-off-by: Eric Sandeen <sandeen@redhat.com> Reviewed-by: Bill O'Donnell <billodo@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* xfs: add some 'static' annotationsEric Biggers2016-10-20
| | | | | | | | | | | | | sparse reported that several variables and a function were not forward-declared anywhere and therefore should be 'static'. Found with sparse by running 'make C=2 CF=-D__CHECK_ENDIAN__ fs/xfs/' Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <david@fromorbit.com>
* xfs: remove redundant assignment of ifpColin Ian King2016-10-20
| | | | | | | | | | | Remove redundant ifp = ifp statement, it does nothing. Found with static analysis by CoverityScan. Signed-off-by: Colin Ian King <colin.king@canonical.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* xfs: rework refcount cow recovery error handlingDarrick J. Wong2016-10-10
| | | | | | | | | | | | The error handling in xfs_refcount_recover_cow_leftovers is confused and can potentially leak memory, so rework it to release resources correctly on error. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reported-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* xfs: implement swapext for rmap filesystemsDarrick J. Wong2016-10-05
| | | | | | | | | | | | | | Implement swapext for filesystems that have reverse mapping. Back in the reflink patches, we augmented the bmap code with a 'REMAP' flag that updates only the bmbt and doesn't touch the allocator and implemented log redo items for those two operations. Now we can rewrite extent swapping as a (looong) series of remap operations. This is far less efficient than the fork swapping method implemented in the past, so we only switch this on for rmap. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: recognize the reflink feature bitDarrick J. Wong2016-10-05
| | | | | | | | Add the reflink feature flag to the set of recognized feature flags. This enables users to write to reflink filesystems. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: simulate per-AG reservations being critically lowDarrick J. Wong2016-10-05
| | | | | | | | | | Create an error injection point that enables us to simulate being critically low on per-AG block reservations. This should enable us to simulate this specific ENOSPC condition so that we can test falling back to a regular file copy. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: don't mix reflink and DAX mode for nowDarrick J. Wong2016-10-05
| | | | | | | | Since we don't have a strategy for handling both DAX and reflink, for now we'll just prohibit both being set at the same time. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: check for invalid inode reflink flagsDarrick J. Wong2016-10-05
| | | | | | | | | We don't support sharing blocks on the realtime device. Flag inodes with the reflink or cowextsize flags set when the reflink feature is disabled. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: convert unwritten status of reverse mappings for shared filesDarrick J. Wong2016-10-05
| | | | | | | | Provide a function to convert an unwritten extent to a real one and vice versa when shared extents are possible. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: use interval query for rmap alloc operations on shared filesDarrick J. Wong2016-10-05
| | | | | | | | | | | When it's possible for reverse mappings to overlap (data fork extents of files on reflink filesystems), use the interval query function to find the left neighbor of an extent we're trying to add; and be careful to use the lookup functions to update the neighbors and/or add new extents. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: add shared rmap map/unmap/convert log item typesDarrick J. Wong2016-10-05
| | | | | | | | | Wire up some rmap log redo item type codes to map, unmap, or convert shared data block extents. The actual log item recovery comes in a later patch. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: increase log reservations for reflinkDarrick J. Wong2016-10-05
| | | | | | | | Increase the log reservations to handle the increased rolling that happens at the end of copy-on-write operations. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: try other AGs to allocate a BMBT blockDarrick J. Wong2016-10-05
| | | | | | | | | | | | | | | | | | | | | Prior to the introduction of reflink, allocating a block and mapping it into a file was performed in a single transaction with a single block reservation, and the allocator was supposed to find enough blocks to allocate the extent and any BMBT blocks that might be necessary (unless we're low on space). However, due to the way copy on write works, allocation and mapping have been split into two transactions, which means that we must be able to handle the case where we allocate an extent for CoW but that AG runs out of free space before the blocks can be mapped into a file, and the mapping requires a new BMBT block. When this happens, look in one of the other AGs for a BMBT block instead of taking the FS down. The same applies to the functions that convert a data fork to extents and later btree format. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: preallocate blocks for worst-case btree expansionDarrick J. Wong2016-10-05
| | | | | | | | | | | | | | | | | | | | | | | | | To gracefully handle the situation where a CoW operation turns a single refcount extent into a lot of tiny ones and then run out of space when a tree split has to happen, use the per-AG reserved block pool to pre-allocate all the space we'll ever need for a maximal btree. For a 4K block size, this only costs an overhead of 0.3% of available disk space. When reflink is enabled, we have an unfortunate problem with rmap -- since we can share a block billions of times, this means that the reverse mapping btree can expand basically infinitely. When an AG is so full that there are no free blocks with which to expand the rmapbt, the filesystem will shut down hard. This is rather annoying to the user, so use the AG reservation code to reserve a "reasonable" amount of space for rmap. We'll prevent reflinks and CoW operations if we think we're getting close to exhausting an AG's free space rather than shutting down, but this permanent reservation should be enough for "most" users. Hopefully. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> [hch@lst.de: ensure that we invalidate the freed btree buffer] Signed-off-by: Christoph Hellwig <hch@lst.de>
* xfs: create a separate cow extent size hint for the allocatorDarrick J. Wong2016-10-05
| | | | | | | | | | | | | | | | | | | | | | Create a per-inode extent size allocator hint for copy-on-write. This hint is separate from the existing extent size hint so that CoW can take advantage of the fragmentation-reducing properties of extent size hints without disabling delalloc for regular writes. The extent size hint that's fed to the allocator during a copy on write operation is the greater of the cowextsize and regular extsize hint. During reflink, if we're sharing the entire source file to the entire destination file and the destination file doesn't already have a cowextsize hint, propagate the source file's cowextsize hint to the destination file. Furthermore, zero the bulkstat buffer prior to setting the fields so that we don't copy kernel memory contents into userspace. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: teach get_bmapx about shared extents and the CoW forkDarrick J. Wong2016-10-05
| | | | | | | | | Teach xfs_getbmapx how to report shared extents and CoW fork contents accurately in the bmap output by querying the refcount btree appropriately. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: store in-progress CoW allocations in the refcount btreeDarrick J. Wong2016-10-05
| | | | | | | | | | | | | | | | | | | | | | | | | | Due to the way the CoW algorithm in XFS works, there's an interval during which blocks allocated to handle a CoW can be lost -- if the FS goes down after the blocks are allocated but before the block remapping takes place. This is exacerbated by the cowextsz hint -- allocated reservations can sit around for a while, waiting to get used. Since the refcount btree doesn't normally store records with refcount of 1, we can use it to record these in-progress extents. In-progress blocks cannot be shared because they're not user-visible, so there shouldn't be any conflicts with other programs. This is a better solution than holding EFIs during writeback because (a) EFIs can't be relogged currently, (b) even if they could, EFIs are bound by available log space, which puts an unnecessary upper bound on how much CoW we can have in flight, and (c) we already have a mechanism to track blocks. At mount time, read the refcount records and free anything we find with a refcount of 1 because those were in-progress when the FS went down. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: support removing extents from CoW forkDarrick J. Wong2016-10-05
| | | | | | | | | | Create a helper method to remove extents from the CoW fork without any of the side effects (rmapbt/bmbt updates) of the regular extent deletion routine. We'll eventually use this to clear out the CoW fork during ioend processing. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: support allocating delayed extents in CoW forkDarrick J. Wong2016-10-04
| | | | | | | | | | Modify xfs_bmap_add_extent_delay_real() so that we can convert delayed allocation extents in the CoW fork to real allocations, and wire this up all the way back to xfs_iomap_write_allocate(). In a subsequent patch, we'll modify the writepage handler to call this. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: support bmapping delalloc extents in the CoW forkDarrick J. Wong2016-10-04
| | | | | | | | | Allow the creation of delayed allocation extents in the CoW fork. In a subsequent patch we'll wire up iomap_begin to actually do this via reflink helper functions. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: introduce the CoW forkDarrick J. Wong2016-10-04
| | | | | | | | | Introduce a new in-core fork for storing copy-on-write delalloc reservations and allocated extents that are in the process of being written out. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: don't allow reflinked dir/dev/fifo/socket/pipe filesDarrick J. Wong2016-10-04
| | | | | | | | Only non-rt files can be reflinked, so check that when we load an inode. Also, don't leak the attr fork if there's a failure. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: add reflink feature flag to geometryDarrick J. Wong2016-10-04
| | | | | | | | Report the reflink feature in the XFS geometry so that xfs_info and friends know the filesystem has this feature. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: return work remaining at the end of a bunmapi operationDarrick J. Wong2016-10-04
| | | | | | | | | | Return the range of file blocks that bunmapi didn't free. This hint is used by CoW and reflink to figure out what part of an extent actually got freed so that it can set up the appropriate atomic remapping of just the freed range. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: implement deferred bmbt map/unmap operationsDarrick J. Wong2016-10-04
| | | | | | | | | Implement deferred versions of the inode block map/unmap functions. These will be used in subsequent patches to make reflink operations atomic. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: pass bmapi flags through to bmap_del_extentDarrick J. Wong2016-10-04
| | | | | | | | | | Pass BMAPI_ flags from bunmapi into bmap_del_extent and extend BMAPI_REMAP (which means "don't touch the allocator or the quota accounting") to apply to bunmapi as well. This will be used to implement the unmap operation, which will be used by swapext. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: map an inode's offset to an exact physical blockDarrick J. Wong2016-10-04
| | | | | | | | | | Teach the bmap routine to know how to map a range of file blocks to a specific range of physical blocks, instead of simply allocating fresh blocks. This enables reflink to map a file to blocks that are already in use. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: log bmap intent itemsDarrick J. Wong2016-10-04
| | | | | | | | | Provide a mechanism for higher levels to create BUI/BUD items, submit them to the log, and a stub function to deal with recovered BUI items. These parts will be connected to the rmapbt in a later patch. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: create bmbt update intent log itemsDarrick J. Wong2016-10-04
| | | | | | | | | | | | Create bmbt update intent/done log items to record redo information in the log. Because we roll transactions multiple times for reflink operations, we also have to track the status of the metadata updates that will be recorded in the post-roll transactions in case we crash before committing the final transaction. This mechanism enables log recovery to finish what was already started. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: introduce reflink utility functionsDarrick J. Wong2016-10-03
| | | | | | | | These functions will be used by the other reflink functions to find the maximum length of a range of shared blocks. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.coM> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: reserve AG space for the refcount btree rootDarrick J. Wong2016-10-03
| | | | | | | | Reduce the max AG usable space size so that we always have space for the refcount btree root. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: adjust refcount when unmapping file blocksDarrick J. Wong2016-10-03
| | | | | | | | | When we're unmapping blocks from a reflinked file, decrease the refcount of the affected blocks and free the extents that are no longer in use. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: connect refcount adjust functions to upper layersDarrick J. Wong2016-10-03
| | | | | | | | Plumb in the upper level interface to schedule and finish deferred refcount operations via the deferred ops mechanism. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: adjust refcount of an extent of blocks in refcount btreeDarrick J. Wong2016-10-03
| | | | | | | | Provide functions to adjust the reference counts for an extent of physical blocks stored in the refcount btree. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
* xfs: log refcount intent itemsDarrick J. Wong2016-10-03
| | | | | | | | | Provide a mechanism for higher levels to create CUI/CUD items, submit them to the log, and a stub function to deal with recovered CUI items. These parts will be connected to the refcountbt in a later patch. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: create refcount update intent log itemsDarrick J. Wong2016-10-03
| | | | | | | | | | | | | Create refcount update intent/done log items to record redo information in the log. Because we need to roll transactions between updating the bmbt mapping and updating the reverse mapping, we also have to track the status of the metadata updates that will be recorded in the post-roll transactions, just in case we crash before committing the final transaction. This mechanism enables log recovery to finish what was already started. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: add refcount btree operationsDarrick J. Wong2016-10-03
| | | | | | | | | | | | | Implement the generic btree operations required to manipulate refcount btree blocks. The implementation is similar to the bmapbt, though it will only allocate and free blocks from the AG. Since the refcount root and level fields are separate from the existing roots and levels array, they need a separate logging flag. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> [hch: fix logging of AGF refcount btree fields] Signed-off-by: Christoph Hellwig <hch@lst.de>
* xfs: account for the refcount btree in the alloc/free log reservationDarrick J. Wong2016-10-03
| | | | | | | | | | | | | | | | | | | | | Every time we allocate or free a data extent, we might need to split the refcount btree. Reserve some blocks in the transaction to handle this possibility. Even though the deferred refcount code can roll a transaction to avoid overloading the transaction, we can still exceed the reservation. Certain pathological workloads (1k blocks, no cowextsize hint, random directio writes), cause a perfect storm wherein a refcount adjustment of a large range of blocks causes full tree splits in two separate extents in two separate refcount tree blocks; allocating new refcount tree blocks causes rmap btree splits; and all the allocation activity causes the freespace btrees to split, blowing the reservation. (Reproduced by generic/167 over NFS atop XFS) Signed-off-by: Christoph Hellwig <hch@lst.de> [darrick.wong@oracle.com: add commit message] Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
* xfs: define the on-disk refcount btree formatDarrick J. Wong2016-10-03
| | | | | | | | | | Start constructing the refcount btree implementation by establishing the on-disk format and everything needed to read, write, and manipulate the refcount btree blocks. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: refcount btree add more reserved blocksDarrick J. Wong2016-10-03
| | | | | | | | | Since XFS reserves a small amount of space in each AG as the minimum free space needed for an operation, save some more space in case we touch the refcount btree. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: introduce refcount btree definitionsDarrick J. Wong2016-10-03
| | | | | | | | Add new per-AG refcount btree definitions to the per-AG structures. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de>
* Merge branch 'xfs-4.9-log-recovery-fixes' into for-nextDave Chinner2016-10-02
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| * xfs: remote attribute blocks aren't really userdataDave Chinner2016-09-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When adding a new remote attribute, we write the attribute to the new extent before the allocation transaction is committed. This means we cannot reuse busy extents as that violates crash consistency semantics. Hence we currently treat remote attribute extent allocation like userdata because it has the same overwrite ordering constraints as userdata. Unfortunately, this also allows the allocator to incorrectly apply extent size hints to the remote attribute extent allocation. This results in interesting failures, such as transaction block reservation overruns and in-memory inode attribute fork corruption. To fix this, we need to separate the busy extent reuse configuration from the userdata configuration. This changes the definition of XFS_BMAPI_METADATA slightly - it now means that allocation is metadata and reuse of busy extents is acceptible due to the metadata ordering semantics of the journal. If this flag is not set, it means the allocation is that has unordered data writeback, and hence busy extent reuse is not allowed. It no longer implies the allocation is for user data, just that the data write will not be strictly ordered. This matches the semantics for both user data and remote attribute block allocation. As such, This patch changes the "userdata" field to a "datatype" field, and adds a "no busy reuse" flag to the field. When we detect an unordered data extent allocation, we immediately set the no reuse flag. We then set the "user data" flags based on the inode fork we are allocating the extent to. Hence we only set userdata flags on data fork allocations now and consider attribute fork remote extents to be an unordered metadata extent. The result is that remote attribute extents now have the expected allocation semantics, and the data fork allocation behaviour is completely unchanged. It should be noted that there may be other ways to fix this (e.g. use ordered metadata buffers for the remote attribute extent data write) but they are more invasive and difficult to validate both from a design and implementation POV. Hence this patch takes the simple, obvious route to fixing the problem... Reported-and-tested-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <david@fromorbit.com>
* | Merge branch 'xfs-4.9-delalloc-rework' into for-nextDave Chinner2016-10-02
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| * | xfs: rewrite and optimize the delalloc write pathChristoph Hellwig2016-09-18
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently xfs_iomap_write_delay does up to lookups in the inode extent tree, which is rather costly especially with the new iomap based write path and small write sizes. But it turns out that the low-level xfs_bmap_search_extents gives us all the information we need in the regular delalloc buffered write path: - it will return us an extent covering the block we are looking up if it exists. In that case we can simply return that extent to the caller and are done - it will tell us if we are beyoned the last current allocated block with an eof return parameter. In that case we can create a delalloc reservation and use the also returned information about the last extent in the file as the hint to size our delalloc reservation. - it can tell us that we are writing into a hole, but that there is an extent beyoned this hole. In this case we can create a delalloc reservation that covers the requested size (possible capped to the next existing allocation). All that can be done in one single routine instead of bouncing up and down a few layers. This reduced the CPU overhead of the block mapping routines and also simplified the code a lot. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* | xfs: set up per-AG free space reservationsDarrick J. Wong2016-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | One unfortunate quirk of the reference count and reverse mapping btrees -- they can expand in size when blocks are written to *other* allocation groups if, say, one large extent becomes a lot of tiny extents. Since we don't want to start throwing errors in the middle of CoWing, we need to reserve some blocks to handle future expansion. The transaction block reservation counters aren't sufficient here because we have to have a reserve of blocks in every AG, not just somewhere in the filesystem. Therefore, create two per-AG block reservation pools. One feeds the AGFL so that rmapbt expansion always succeeds, and the other feeds all other metadata so that refcountbt expansion never fails. Use the count of how many reserved blocks we need to have on hand to create a virtual reservation in the AG. Through selective clamping of the maximum length of allocation requests and of the length of the longest free extent, we can make it look like there's less free space in the AG unless the reservation owner is asking for blocks. In other words, play some accounting tricks in-core to make sure that we always have blocks available. On the plus side, there's nothing to clean up if we crash, which is contrast to the strategy that the rough draft used (actually removing extents from the freespace btrees). Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
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