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Add a metadir path to select the realtime refcount btree inode and load
it at mount time. The rtrefcountbt inode will have a unique extent format
code, which means that we also have to update the inode validation and
flush routines to look for it.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Extend the refcount update (CUI) log items with a new realtime flag that
indicates that the updates apply against the realtime refcountbt. We'll
wire up the actual refcount code later.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Prepare the high-level refcount functions to deal with the new realtime
refcountbt and its slightly different conventions. Provide the ability
to talk to either refcountbt or rtrefcountbt formats from the same high
level code.
Note that we leave the _recover_cow_leftovers functions for a separate
patch so that we can convert it all at once.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Implement the generic btree operations needed to manipulate rtrefcount
btree blocks. This is different from the regular refcountbt in that we
allocate space from the filesystem at large, and are neither constrained
to the free space nor any particular AG.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Make sure that there's enough log reservation to handle mapping
and unmapping realtime extents. We have to reserve enough space
to handle a split in the rtrefcountbt to add the record and a second
split in the regular refcountbt to record the rtrefcountbt split.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Add the ondisk structure definitions for realtime refcount btrees. The
realtime refcount btree will be rooted from a hidden inode so it needs
to have a separate btree block magic and pointer format.
Next, add everything needed to read, write and manipulate refcount btree
blocks. This prepares the way for connecting the btree operations
implementation, though the changes to actually root the rtrefcount btree
in an inode come later.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Actually namespace these variables properly, so that readers can tell
that this is an XFS symbol, and that it's for the refcount
functionality.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Create an in-memory btree of rmap records instead of an array. This
enables us to do live record collection instead of freezing the fs.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Repair the realtime rmap btree while mounted. Similar to the regular
rmap btree repair code, we walk the data fork mappings of every realtime
file in the filesystem to collect reverse-mapping records in an xfarray.
Then we sort the xfarray, and use the btree bulk loader to create a new
rtrmap btree ondisk. Finally, we swap the btree roots, and reap the old
blocks in the usual way.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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For a given rt group, regenerate the bitmap contents from the group's
realtime rmap btree.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Add a new XFS_SCRUB_METAPATH subtype so that we can scrub the metadata
directory tree path to the rmap btree file for each rt group.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Check the realtime reverse mapping btree against the rtbitmap, and
modify the rtbitmap scrub to check against the rtrmapbt.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Whenever we encounter corrupt realtime rmap btree blocks, we should
report that to the health monitoring system for later reporting.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Create a library routine to allocate and initialize an empty realtime
rmapbt inode. We'll use this for mkfs and repair.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Connect the map and unmap reverse-mapping operations to the realtime
rmapbt via the deferred operation callbacks. This enables us to
perform rmap operations against the correct btree.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Plumb in the pieces we need to embed the root of the realtime rmap btree
in an inode's data fork, complete with new metafile type and on-disk
interpretation functions.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Reserve some free blocks so that we will always have enough free blocks
in the data volume to handle expansion of the realtime rmap btree.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Add a metadir path to select the realtime rmap btree inode and load
it at mount time. The rtrmapbt inode will have a unique extent format
code, which means that we also have to update the inode validation and
flush routines to look for it.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Create a new fork format type for metadata btrees. This fork type
requires that the inode is in the metadata directory tree, and only
applies to the data fork. The actual type of the metadata btree itself
is determined by the di_metatype field.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Create a helper function to turn a metadata file type code into a
printable string, and use this to complain about lockdep problems with
rtgroup inodes. We'll use this more in the next patch.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Extend the rmap update (RUI) log items to handle realtime volumes by
adding a new log intent item type.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Prepare the high-level rmap functions to deal with the new realtime
rmapbt and its slightly different conventions. Provide the ability
to talk to either rmapbt or rtrmapbt formats from the same high
level code.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Implement the generic btree operations needed to manipulate rtrmap
btree blocks. This is different from the regular rmapbt in that we
allocate space from the filesystem at large, and are neither
constrained to the free space nor any particular AG.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Make sure that there's enough log reservation to handle mapping
and unmapping realtime extents. We have to reserve enough space
to handle a split in the rtrmapbt to add the record and a second
split in the regular rmapbt to record the rtrmapbt split.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Add the ondisk structure definitions for realtime rmap btrees. The
realtime rmap btree will be rooted from a hidden inode so it needs to
have a separate btree block magic and pointer format.
Next, add everything needed to read, write and manipulate rmap btree
blocks. This prepares the way for connecting the btree operations
implementation, though embedding the rtrmap btree root in the inode
comes later in the series.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Create a new space reservation scheme so that btree metadata for the
realtime volume can reserve space in the data device to avoid space
underruns.
Back when we were testing the rmap and refcount btrees for the data
device, people observed occasional shutdowns when xfs_btree_split was
called for either of those two btrees. This happened when certain
operations (mostly writeback ioends) created new rmap or refcount
records, which would expand the size of the btree. If there were no
free blocks available the allocation would fail and the split would shut
down the filesystem.
I considered pre-reserving blocks for btree expansion at the time of a
write() call, but there wasn't any good way to attach the reservations
to an inode and keep them there all the way to ioend processing. Unlike
delalloc reservations which have that indlen mechanism, there's no way
to do that for mapped extents; and indlen blocks are given back during
the delalloc -> unwritten transition.
The solution was to reserve sufficient blocks for rmap/refcount btree
expansion at mount time. This is what the XFS_AG_RESV_* flags provide;
any expansion of those two btrees can come from the pre-reserved space.
This patch brings that pre-reservation ability to inode-rooted btrees so
that the rt rmap and refcount btrees can also save room for future
expansion.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Add the necessary flags and code so that we can support storing leaf
records in the inode root block of a btree. This hasn't been necessary
before, but the realtime rmapbt will need to be able to do this.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Simplify the calling conventions by allowing callers to pass a fsbno
(xfs_fsblock_t) directly into these functions, since we're just going to
set it in a struct anyway.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Files participating in the metadata directory tree are not accounted to
the quota subsystem. Therefore, the i_[ugp]dquot pointers in struct
xfs_inode are never used and should always be NULL.
In the next patch we want to add a u64 count of fs blocks reserved for
metadata btree expansion, but we don't want every inode in the fs to pay
the memory price for this feature. The intent is to union those three
pointers with the u64 counter, but for that to work we must guard
against all access to the dquot pointers for metadata files.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Create some simple helpers to reduce the amount of typing whenever we
access rtgroup inodes. Conversion was done with this spatch and some
minor reformatting:
@@
expression rtg;
@@
- rtg->rtg_inodes[XFS_RTGI_BITMAP]
+ rtg_bitmap(rtg)
@@
expression rtg;
@@
- rtg->rtg_inodes[XFS_RTGI_SUMMARY]
+ rtg_summary(rtg)
and the CLI command:
$ spatch --sp-file /tmp/moo.cocci --dir fs/xfs/ --use-gitgrep --in-place
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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In preparation for allowing records in an inode btree root, hoist the
code that copies keyptrs from an existing node child into the root block
to a separate function. Remove some unnecessary conditionals and clean
up a few function calls in the new function. Note that this change
reorders the ->free_block call with respect to the change in bc_nlevels
to make it easier to support inode root leaf blocks in the next patch.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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In preparation for allowing records in an inode btree root, hoist the
code that copies keyptrs from an existing node root into a child block
to a separate function. Note that the new function explicitly computes
the keys of the new child block and stores that in the root block; while
the bmap btree could rely on leaving the key alone, realtime rmap needs
to set the new high key.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Hoist out the code that migrates broot pointers during a resize
operation to avoid code duplication and streamline the caller. Also
use the correct bmbt pointer type for the sizeof operation.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Move the inode fork btree root reallocation function part of the btree
ops because it's now mostly bmbt-specific code.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Change the calling signature of xfs_iroot_realloc to take the ifork and
the new number of records in the btree block, not a diff against the
current number. This will make the callsites easier to understand.
Note that this function is misnamed because it is very specific to the
single type of inode-rooted btree supported. This will be addressed in
a subsequent patch.
Return the new btree root to reduce the amount of code clutter.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Hoist the code that allocates, frees, and reallocates if_broot into a
single xfs_iroot_krealloc function. Eventually we're going to push
xfs_iroot_realloc into the btree ops structure to handle multiple
inode-rooted btrees, but first let's separate out the bits that should
stay in xfs_inode_fork.c.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Tidy up this function a bit before we start refactoring the memory
handling and move the function to the bmbt code.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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V4 symlink blocks didn't have headers, so return early if this is a V4
filesystem.
Cc: <stable@vger.kernel.org> # v5.1
Fixes: 39708c20ab5133 ("xfs: miscellaneous verifier magic value fixups")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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For a sparse inodes filesystem, mkfs.xfs computes the values of
sb_spino_align and sb_inoalignmt with the following code:
int cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
if (cfg->sb_feat.crcs_enabled)
cluster_size *= cfg->inodesize / XFS_DINODE_MIN_SIZE;
sbp->sb_spino_align = cluster_size >> cfg->blocklog;
sbp->sb_inoalignmt = XFS_INODES_PER_CHUNK *
cfg->inodesize >> cfg->blocklog;
On a V5 filesystem with 64k fsblocks and 512 byte inodes, this results
in cluster_size = 8192 * (512 / 256) = 16384. As a result,
sb_spino_align and sb_inoalignmt are both set to zero. Unfortunately,
this trips the new sb_spino_align check that was just added to
xfs_validate_sb_common, and the mkfs fails:
# mkfs.xfs -f -b size=64k, /dev/sda
meta-data=/dev/sda isize=512 agcount=4, agsize=81136 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=1
= reflink=1 bigtime=1 inobtcount=1 nrext64=1
= exchange=0 metadir=0
data = bsize=65536 blocks=324544, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=65536 ascii-ci=0, ftype=1, parent=0
log =internal log bsize=65536 blocks=5006, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=65536 blocks=0, rtextents=0
= rgcount=0 rgsize=0 extents
Discarding blocks...Sparse inode alignment (0) is invalid.
Metadata corruption detected at 0x560ac5a80bbe, xfs_sb block 0x0/0x200
libxfs_bwrite: write verifier failed on xfs_sb bno 0x0/0x1
mkfs.xfs: Releasing dirty buffer to free list!
found dirty buffer (bulk) on free list!
Sparse inode alignment (0) is invalid.
Metadata corruption detected at 0x560ac5a80bbe, xfs_sb block 0x0/0x200
libxfs_bwrite: write verifier failed on xfs_sb bno 0x0/0x1
mkfs.xfs: writing AG headers failed, err=22
Prior to commit 59e43f5479cce1 this all worked fine, even if "sparse"
inodes are somewhat meaningless when everything fits in a single
fsblock. Adjust the checks to handle existing filesystems.
Cc: <stable@vger.kernel.org> # v6.13-rc1
Fixes: 59e43f5479cce1 ("xfs: sb_spino_align is not verified")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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In commit 2c813ad66a72, I partially fixed a bug wherein xfs_btree_insrec
would erroneously try to update the parent's key for a block that had
been split if we decided to insert the new record into the new block.
The solution was to detect this situation and update the in-core key
value that we pass up to the caller so that the caller will (eventually)
add the new block to the parent level of the tree with the correct key.
However, I missed a subtlety about the way inode-rooted btrees work. If
the full block was a maximally sized inode root block, we'll solve that
fullness by moving the root block's records to a new block, resizing the
root block, and updating the root to point to the new block. We don't
pass a pointer to the new block to the caller because that work has
already been done. The new record will /always/ land in the new block,
so in this case we need to use xfs_btree_update_keys to update the keys.
This bug can theoretically manifest itself in the very rare case that we
split a bmbt root block and the new record lands in the very first slot
of the new block, though I've never managed to trigger it in practice.
However, it is very easy to reproduce by running generic/522 with the
realtime rmapbt patchset if rtinherit=1.
Cc: <stable@vger.kernel.org> # v4.8
Fixes: 2c813ad66a7218 ("xfs: support btrees with overlapping intervals for keys")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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smatch reported that we screwed up the error cleanup in this function.
Fix it.
Cc: <stable@vger.kernel.org> # v6.13-rc1
Fixes: ae897e0bed0f54 ("xfs: support creating per-RTG files in growfs")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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With the nrext64 feature enabled, it's possible for a data fork to have
2^48 extent mappings. Even with a 64k fsblock size, that maps out to
a bmbt containing more than 2^32 blocks. Therefore, this predicate must
return a u64 count to avoid an integer wraparound that will cause scrub
to do the wrong thing.
It's unlikely that any such filesystem currently exists, because the
incore bmbt would consume more than 64GB of kernel memory on its own,
and so far nobody except me has driven a filesystem that far, judging
from the lack of complaints.
Cc: <stable@vger.kernel.org> # v5.19
Fixes: df9ad5cc7a5240 ("xfs: Introduce macros to represent new maximum extent counts for data/attr forks")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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xfs_bmap_add_extent_hole_delay works entirely on delalloc extents, for
which xfs_bmap_same_rtgroup doesn't make sense.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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The runt AG at the end of a filesystem is almost always smaller than
the mp->m_sb.sb_agblocks. Unfortunately, when setting the max_agbno
limit for the inode chunk allocation, we do not take this into
account. This means we can allocate a sparse inode chunk that
overlaps beyond the end of an AG. When we go to allocate an inode
from that sparse chunk, the irec fails validation because the
agbno of the start of the irec is beyond valid limits for the runt
AG.
Prevent this from happening by taking into account the size of the
runt AG when allocating inode chunks. Also convert the various
checks for valid inode chunk agbnos to use xfs_ag_block_count()
so that they will also catch such issues in the future.
Fixes: 56d1115c9bc7 ("xfs: allocate sparse inode chunks on full chunk allocation failure")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Compat features are new features that older kernels can safely ignore,
allowing read-write mounts without issues. The current sb write validation
implementation returns -EFSCORRUPTED for unknown compat features,
preventing filesystem write operations and contradicting the feature's
definition.
Additionally, if the mounted image is unclean, the log recovery may need
to write to the superblock. Returning an error for unknown compat features
during sb write validation can cause mount failures.
Although XFS currently does not use compat feature flags, this issue
affects current kernels' ability to mount images that may use compat
feature flags in the future.
Since superblock read validation already warns about unknown compat
features, it's unnecessary to repeat this warning during write validation.
Therefore, the relevant code in write validation is being removed.
Fixes: 9e037cb7972f ("xfs: check for unknown v5 feature bits in superblock write verifier")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Long Li <leo.lilong@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Pull xfs updates from Carlos Maiolino:
"The bulk of this pull request is a major rework that Darrick and
Christoph have been doing on XFS's real-time volume, coupled with a
few features to support this rework. It does also includes some bug
fixes.
- convert perag to use xarrays
- create a new generic allocation group structure
- add metadata inode dir trees
- create in-core rt allocation groups
- shard the RT section into allocation groups
- persist quota options with the enw metadata dir tree
- enable quota for RT volumes
- enable metadata directory trees
- some bugfixes"
* tag 'xfs-6.13-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (146 commits)
xfs: port ondisk structure checks from xfs/122 to the kernel
xfs: separate space btree structures in xfs_ondisk.h
xfs: convert struct typedefs in xfs_ondisk.h
xfs: enable metadata directory feature
xfs: enable realtime quota again
xfs: update sb field checks when metadir is turned on
xfs: reserve quota for realtime files correctly
xfs: create quota preallocation watermarks for realtime quota
xfs: report realtime block quota limits on realtime directories
xfs: persist quota flags with metadir
xfs: advertise realtime quota support in the xqm stat files
xfs: scrub quota file metapaths
xfs: fix chown with rt quota
xfs: use metadir for quota inodes
xfs: refactor xfs_qm_destroy_quotainos
xfs: use rtgroup busy extent list for FITRIM
xfs: implement busy extent tracking for rtgroups
xfs: port the perag discard code to handle generic groups
xfs: move the min and max group block numbers to xfs_group
xfs: adjust min_block usage in xfs_verify_agbno
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs multigrain timestamps from Christian Brauner:
"This is another try at implementing multigrain timestamps. This time
with significant help from the timekeeping maintainers to reduce the
performance impact.
Thomas provided a base branch that contains the required timekeeping
interfaces for the VFS. It serves as the base for the multi-grain
timestamp work:
- Multigrain timestamps allow the kernel to use fine-grained
timestamps when an inode's attributes is being actively observed
via ->getattr(). With this support, it's possible for a file to get
a fine-grained timestamp, and another modified after it to get a
coarse-grained stamp that is earlier than the fine-grained time. If
this happens then the files can appear to have been modified in
reverse order, which breaks VFS ordering guarantees.
To prevent this, a floor value is maintained for multigrain
timestamps. Whenever a fine-grained timestamp is handed out, record
it, and when later coarse-grained stamps are handed out, ensure
they are not earlier than that value. If the coarse-grained
timestamp is earlier than the fine-grained floor, return the floor
value instead.
The timekeeper changes add a static singleton atomic64_t into
timekeeper.c that is used to keep track of the latest fine-grained
time ever handed out. This is tracked as a monotonic ktime_t value
to ensure that it isn't affected by clock jumps. Because it is
updated at different times than the rest of the timekeeper object,
the floor value is managed independently of the timekeeper via a
cmpxchg() operation, and sits on its own cacheline.
Two new public timekeeper interfaces are added:
(1) ktime_get_coarse_real_ts64_mg() fills a timespec64 with the
later of the coarse-grained clock and the floor time
(2) ktime_get_real_ts64_mg() gets the fine-grained clock value,
and tries to swap it into the floor. A timespec64 is filled
with the result.
- The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around
1 per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting
via NFSv3, which relies on timestamps to validate caches. A lot of
changes can happen in a jiffy, so timestamps aren't sufficient to
help the client decide when to invalidate the cache. Even with
NFSv4, a lot of exported filesystems don't properly support a
change attribute and are subject to the same problems with
timestamp granularity. Other applications have similar issues with
timestamps (e.g backup applications).
If we were to always use fine-grained timestamps, that would
improve the situation, but that becomes rather expensive, as the
underlying filesystem would have to log a lot more metadata
updates.
This adds a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in
inode->i_ctime_nsec as a flag that indicates whether the current
timestamps have been queried via stat() or the like. When it's set,
we allow the kernel to use a fine-grained timestamp iff it's
necessary to make the ctime show a different value.
This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible
for a file being changed to get a fine-grained timestamp. A file
that is altered just a bit later can then get a coarse-grained one
that appears older than the earlier fine-grained time. This
violates timestamp ordering guarantees.
This is where the earlier mentioned timkeeping interfaces help. A
global monotonic atomic64_t value is kept that acts as a timestamp
floor. When we go to stamp a file, we first get the latter of the
current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it
with that value.
If it has been queried, then first see whether the current coarse
time is later than the existing ctime. If it is, then we accept
that value. If it isn't, then we get a fine-grained time and try to
swap that into the global floor. Whether that succeeds or fails, we
take the resulting floor time, convert it to realtime and try to
swap that into the ctime.
We take the result of the ctime swap whether it succeeds or fails,
since either is just as valid.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same
floor value as multigrain filesystems)"
* tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: reduce pointer chasing in is_mgtime() test
tmpfs: add support for multigrain timestamps
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
Documentation: add a new file documenting multigrain timestamps
fs: add percpu counters for significant multigrain timestamp events
fs: tracepoints around multigrain timestamp events
fs: handle delegated timestamps in setattr_copy_mgtime
timekeeping: Add percpu counter for tracking floor swap events
timekeeping: Add interfaces for handling timestamps with a floor value
fs: have setattr_copy handle multigrain timestamps appropriately
fs: add infrastructure for multigrain timestamps
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into staging-merge
xfs: improve ondisk structure checks [v5.5 10/10]
Reorganize xfs_ondisk.h to group the build checks by type, then add a
bunch of missing checks that were in xfs/122 but not the build system.
With this, we can get rid of xfs/122.
With a bit of luck, this should all go splendidly.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into staging-merge
xfs: enable metadir [v5.5 09/10]
Actually enable this very large feature, which adds metadata directory
trees, allocation groups on the realtime volume, persistent quota
options, and quota for realtime files.
With a bit of luck, this should all go splendidly.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into staging-merge
xfs: persist quota options with metadir [v5.5 07/10]
Store the quota files in the metadata directory tree instead of the
superblock. Since we're introducing a new incompat feature flag, let's
also make the mount process bring up quotas in whatever state they were
when the filesystem was last unmounted, instead of requiring sysadmins
to remember that themselves.
With a bit of luck, this should all go splendidly.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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