According to the glibc compat header for Irix 4, these ioctls originated
in April 1991 as a (somewhat clunky) way to preallocate space at the end
of a file on an EFS filesystem. XFS, which was released in Irix 5.3 in
December 1993, picked up these ioctls to maintain compatibility and they
were ported to Linux in the early 2000s.
Recently it was pointed out to me they still lurk in the kernel, even
though the Linux fallocate syscall supplanted the functionality a long
time ago. fstests doesn't seem to include any real functional or stress
tests for these ioctls, which means that the code quality is ... very
questionable. Most notably, it was a stale disk block exposure vector
for 21 years and nobody noticed or complained. As mature programmers
say, "If you're not testing it, it's broken."
Given all that, let's withdraw these ioctls from the XFS userspace API.
Normally we'd set a long deprecation process, but I estimate that there
aren't any real users, so let's trigger a warning in dmesg and return
-ENOTTY.
See: CVE-2021-4155
Augments: 983d8e60f5 ("xfs: map unwritten blocks in XFS_IOC_{ALLOC,FREE}SP just like fallocate")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
By open coding xfs_bmap_last_extent instead of calling it through a
double indirection we don't need to handle an error return that
can't happen given that we are guaranteed to have the extent list in
memory already. Also simplify the calling conventions a little and
move the extent list assert from the only caller into the function.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Remove xfs_zero_file_space and reorganize xfs_file_fallocate so that a
single call to xfs_alloc_file_space covers all modes that preallocate
blocks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
On a sub-page block size filesystem, fsx is failing with a data
corruption after a series of operations involving copying a file
with the destination offset beyond EOF of the destination of the file:
8093(157 mod 256): TRUNCATE DOWN from 0x7a120 to 0x50000 ******WWWW
8094(158 mod 256): INSERT 0x25000 thru 0x25fff (0x1000 bytes)
8095(159 mod 256): COPY 0x18000 thru 0x1afff (0x3000 bytes) to 0x2f400
8096(160 mod 256): WRITE 0x5da00 thru 0x651ff (0x7800 bytes) HOLE
8097(161 mod 256): COPY 0x2000 thru 0x5fff (0x4000 bytes) to 0x6fc00
The second copy here is beyond EOF, and it is to sub-page (4k) but
block aligned (1k) offset. The clone runs the EOF zeroing, landing
in a pre-existing post-eof delalloc extent. This zeroes the post-eof
extents in the page cache just fine, dirtying the pages correctly.
The problem is that xfs_reflink_remap_prep() now truncates the page
cache over the range that it is copying it to, and rounds that down
to cover the entire start page. This removes the dirty page over the
delalloc extent from the page cache without having written it back.
Hence later, when the page cache is flushed, the page at offset
0x6f000 has not been written back and hence exposes stale data,
which fsx trips over less than 10 operations later.
Fix this by changing xfs_reflink_remap_prep() to use
xfs_flush_unmap_range().
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Remove the verbose license text from XFS files and replace them
with SPDX tags. This does not change the license of any of the code,
merely refers to the common, up-to-date license files in LICENSES/
This change was mostly scripted. fs/xfs/Makefile and
fs/xfs/libxfs/xfs_fs.h were modified by hand, the rest were detected
and modified by the following command:
for f in `git grep -l "GNU General" fs/xfs/` ; do
echo $f
cat $f | awk -f hdr.awk > $f.new
mv -f $f.new $f
done
And the hdr.awk script that did the modification (including
detecting the difference between GPL-2.0 and GPL-2.0+ licenses)
is as follows:
$ cat hdr.awk
BEGIN {
hdr = 1.0
tag = "GPL-2.0"
str = ""
}
/^ \* This program is free software/ {
hdr = 2.0;
next
}
/any later version./ {
tag = "GPL-2.0+"
next
}
/^ \*\// {
if (hdr > 0.0) {
print "// SPDX-License-Identifier: " tag
print str
print $0
str=""
hdr = 0.0
next
}
print $0
next
}
/^ \* / {
if (hdr > 1.0)
next
if (hdr > 0.0) {
if (str != "")
str = str "\n"
str = str $0
next
}
print $0
next
}
/^ \*/ {
if (hdr > 0.0)
next
print $0
next
}
// {
if (hdr > 0.0) {
if (str != "")
str = str "\n"
str = str $0
next
}
print $0
}
END { }
$
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Instead of passing in a formatter callback allocate the bmap buffer
in the caller and process the entries there. Additionally replace
the in-kernel buffer with a new much smaller structure, and unify
the implementation of the different ioctls in a single function.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Various utility functions and interfaces that iterate internal
devices try to reference the realtime device even when RT support is
not compiled into the kernel.
Make sure this code is excluded from the CONFIG_XFS_RT=n build,
and where appropriate stub functions to return fatal errors if
they ever get called when RT support is not present.
Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This avoids poking into the internals of the extent list. Also return
the number of extents as the return value instead of an additional
by reference argument, and make it available to callers outside of
xfs_bmap_util.c
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Refactor the inode fork block counting function to count extents for us
at the same time. This will be used by the bmbt scrubber function.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
The "full" argument was used only by the fiemap formatter,
which is now gone with the iomap updates.
Remove the unused arg.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
xfs_free_eofblocks() requires the IOLOCK_EXCL lock, but is called from
different contexts where the lock may or may not be held. The
need_iolock parameter exists for this reason, to indicate whether
xfs_free_eofblocks() must acquire the iolock itself before it can
proceed.
This is ugly and confusing. Simplify the semantics of
xfs_free_eofblocks() to require the caller to acquire the iolock
appropriately and kill the need_iolock parameter. While here, the mp
param can be removed as well as the xfs_mount is accessible from the
xfs_inode structure. This patch does not change behavior.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Drop the compatibility shims that we were using to integrate the new
deferred operation mechanism into the existing code. No new code.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Restructure everything that used xfs_bmap_free to use xfs_defer_ops
instead. For now we'll just remove the old symbols and play some
cpp magic to make it work; in the next patch we'll actually rename
everything.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
In struct xfs_bmap_free, convert the open-coded free extent list to
a regular list, then use list_sort to sort it prior to processing.
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>
Al Viro noticed that xfs_lock_inodes should be static, and
that led to ... a few more.
These are just the easy ones, others require moving functions
higher in source files, so that's not done here to keep
this review simple.
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This patch implements fallocate's FALLOC_FL_INSERT_RANGE for XFS.
1) Make sure that both offset and len are block size aligned.
2) Update the i_size of inode by len bytes.
3) Compute the file's logical block number against offset. If the computed
block number is not the starting block of the extent, split the extent
such that the block number is the starting block of the extent.
4) Shift all the extents which are lying bewteen [offset, last allocated extent]
towards right by len bytes. This step will make a hole of len bytes
at offset.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This function is used libxfs code, but is implemented separately in
userspace. Move the function prototype to xfs_bmap.h so that the
prototype is shared even if the implementations aren't.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
It no long is used for stack splits, so strip the kernel workqueue
bits from it and push it back into libxfs/xfs_bmap.h so that
it can be shared with the userspace code.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
The allocation stack switch at xfs_bmapi_allocate() has served it's
purpose, but is no longer a sufficient solution to the stack usage
problem we have in the XFS allocation path.
Whilst the kernel stack size is now 16k, that is not a valid reason
for undoing all our "keep stack usage down" modifications. What it
does allow us to do is have the freedom to refine and perfect the
modifications knowing that if we get it wrong it won't blow up in
our faces - we have a safety net now.
This is important because we still have the issue of older kernels
having smaller stacks and that they are still supported and are
demonstrating a wide range of different stack overflows. Red Hat
has several open bugs for allocation based stack overflows from
directory modifications and direct IO block allocation and these
problems still need to be solved. If we can solve them upstream,
then distro's won't need to bake their own unique solutions.
To that end, I've observed that every allocation based stack
overflow report has had a specific characteristic - it has happened
during or directly after a bmap btree block split. That event
requires a new block to be allocated to the tree, and so we
effectively stack one allocation stack on top of another, and that's
when we get into trouble.
A further observation is that bmap btree block splits are much rarer
than writeback allocation - over a range of different workloads I've
observed the ratio of bmap btree inserts to splits ranges from 100:1
(xfstests run) to 10000:1 (local VM image server with sparse files
that range in the hundreds of thousands to millions of extents).
Either way, bmap btree split events are much, much rarer than
allocation events.
Finally, we have to move the kswapd state to the allocation workqueue
work when allocation is done on behalf of kswapd. This is proving to
cause significant perturbation in performance under memory pressure
and appears to be generating allocation deadlock warnings under some
workloads, so avoiding the use of a workqueue for the majority of
kswapd writeback allocation will minimise the impact of such
behaviour.
Hence it makes sense to move the stack switch to xfs_btree_split()
and only do it for bmap btree splits. Stack switches during
allocation will be much rarer, so there won't be significant
performacne overhead caused by switching stacks. The worse case
stack from all allocation paths will be split, not just writeback.
And the majority of memory allocations will be done in the correct
context (e.g. kswapd) without causing additional latency, and so we
simplify the memory reclaim interactions between processes,
workqueues and kswapd.
The worst stack I've been able to generate with this patch in place
is 5600 bytes deep. It's very revealing because we exit XFS at:
37) 1768 64 kmem_cache_alloc+0x13b/0x170
about 1800 bytes of stack consumed, and the remaining 3800 bytes
(and 36 functions) is memory reclaim, swap and the IO stack. And
this occurs in the inode allocation from an open(O_CREAT) syscall,
not writeback.
The amount of stack being used is much less than I've previously be
able to generate - fs_mark testing has been able to generate stack
usage of around 7k without too much trouble; with this patch it's
only just getting to 5.5k. This is primarily because the metadata
allocation paths (e.g. directory blocks) are no longer causing
double splits on the same stack, and hence now stack tracing is
showing swapping being the worst stack consumer rather than XFS.
Performance of fs_mark inode create workloads is unchanged.
Performance of fs_mark async fsync workloads is consistently good
with context switches reduced by around 150,000/s (30%).
Performance of dbench, streaming IO and postmark is unchanged.
Allocation deadlock warnings have not been seen on the workloads
that generated them since adding this patch.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This reverts commit 1f6d64829d.
This commit resulted in regressions in performance in low
memory situations where kswapd was doing writeback of delayed
allocation blocks. It resulted in significant parallelism of the
kswapd work and with the special kswapd flags meant that hundreds of
active allocation could dip into kswapd specific memory reserves and
avoid being throttled. This cause a large amount of performance
variation, as well as random OOM-killer invocations that didn't
previously exist.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Upon memory pressure, kswapd calls xfs_vm_writepage() from
shrink_page_list(). This can result in delayed allocation occurring
and that gets deferred to the the allocation workqueue.
The allocation then runs outside kswapd context, which means if it
needs memory (and it does to demand page metadata from disk) it can
block in shrink_inactive_list() waiting for IO congestion. These
blocking waits are normally avoiding in kswapd context, so under
memory pressure writeback from kswapd can be arbitrarily delayed by
memory reclaim.
To avoid this, pass the kswapd context to the allocation being done
by the workqueue, so that memory reclaim understands correctly that
the work is being done for kswapd and therefore it is not blocked
and does not delay memory reclaim.
To avoid issues with int->char conversion of flag fields (as noticed
in v1 of this patch) convert the flag fields in the struct
xfs_bmalloca to bool types. pahole indicates these variables are
still single byte variables, so no extra space is consumed by this
change.
cc: <stable@vger.kernel.org>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This patch implements fallocate's FALLOC_FL_COLLAPSE_RANGE for XFS.
The semantics of this flag are following:
1) It collapses the range lying between offset and length by removing any data
blocks which are present in this range and than updates all the logical
offsets of extents beyond "offset + len" to nullify the hole created by
removing blocks. In short, it does not leave a hole.
2) It should be used exclusively. No other fallocate flag in combination.
3) Offset and length supplied to fallocate should be fs block size aligned
in case of xfs and ext4.
4) Collaspe range does not work beyond i_size.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Now that only one caller of xfs_change_file_space is left it can be merged
into said caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Call xfs_alloc_file_space or xfs_free_file_space directly from
xfs_file_fallocate instead of going through xfs_change_file_space.
This simplified the code by removing the unessecary marshalling of the
arguments into an xfs_flock64_t structure and allows removing checks that
are already done in the VFS code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
So we don't need xfs_dfrag.h in userspace anymore, move the extent
swap ioctl structure definition to xfs_fs.h where most of the other
ioctl structure definitions are.
Now that we don't need separate files for extent swapping, separate
the basic file descriptor checking code to xfs_ioctl.c, and the code
that does the extent swap operation to xfs_bmap_util.c. This
cleanly separates the user interface code from the physical
mechanism used to do the extent swap.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Now we have xfs_inode.c for holding kernel-only XFS inode
operations, move all the inode operations from xfs_vnodeops.c to
this new file as it holds another set of kernel-only inode
operations. The name of this file traces back to the days of Irix
and it's vnodes which we don't have anymore.
Essentially this move consolidates the inode locking functions
and a bunch of XFS inode operations into the one file. Eventually
the high level functions will be merged into the VFS interface
functions in xfs_iops.c.
This leaves only internal preallocation, EOF block manipulation and
hole punching functions in vnodeops.c. Move these to xfs_bmap_util.c
where we are already consolidating various in-kernel physical extent
manipulation and querying functions.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
There is a bunch of code in xfs_bmap.c that is kernel specific and
not shared with userspace. To minimise the difference between the
kernel and userspace code, shift this unshared code to
xfs_bmap_util.c, and the declarations to xfs_bmap_util.h.
The biggest issue here is xfs_bmap_finish() - userspace has it's own
definition of this function, and so we need to move it out of
xfs_bmap.[ch]. This means several other files need to include
xfs_bmap_util.h as well.
It also introduces and interesting dance for the stack switching
code in xfs_bmapi_allocate(). The stack switching/workqueue code is
actually moved to xfs_bmap_util.c, so that userspace can simply use
a #define in a header file to connect the dots without needing to
know about the stack switch code at all.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
