xfs: don't allocate into the data fork for an unshare request

For an unshare request, we only have to take action if the data fork has
a shared mapping. We don't care if someone else set up a cow o

xfs: don't allocate into the data fork for an unshare request

For an unshare request, we only have to take action if the data fork has
a shared mapping. We don't care if someone else set up a cow operation.
If we find nothing in the data fork, return a hole to avoid allocating
space.

Note that fallocate will replace the delalloc reservation with an
unwritten extent anyway, so this has no user-visible effects outside of
avoiding unnecessary updates.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

show more ...

xfs: pass the correct cursor to xfs_iomap_prealloc_size

In xfs_buffered_write_iomap_begin, @icur is the iext cursor for the data
fork and @ccur is the cursor for the cow fork. Pass in whichever cur

xfs: pass the correct cursor to xfs_iomap_prealloc_size

In xfs_buffered_write_iomap_begin, @icur is the iext cursor for the data
fork and @ccur is the cursor for the cow fork. Pass in whichever cursor
corresponds to allocfork, because otherwise the xfs_iext_prev_extent
call can use the data fork cursor to walk off the end of the cow fork
structure. Best case it returns the wrong results, worst case it does
this:

stack segment: 0000 [#1] PREEMPT SMP
CPU: 2 PID: 3141909 Comm: fsstress Tainted: G W 6.3.0-rc2-xfsx #6.3.0-rc2 7bf5cc2e98997627cae5c930d890aba3aeec65dd
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20171121_152543-x86-ol7-builder-01.us.oracle.com-4.el7.1 04/01/2014
RIP: 0010:xfs_iext_prev+0x71/0x150 [xfs]
RSP: 0018:ffffc90002233aa8 EFLAGS: 00010297
RAX: 000000000000000f RBX: 000000000000000e RCX: 000000000000000c
RDX: 0000000000000002 RSI: 000000000000000e RDI: ffff8883d0019ba0
RBP: 989642409af8a7a7 R08: ffffea0000000001 R09: 0000000000000002
R10: 0000000000000000 R11: 000000000000000c R12: ffffc90002233b00
R13: ffff8883d0019ba0 R14: 989642409af8a6bf R15: 000ffffffffe0000
FS: 00007fdf8115f740(0000) GS:ffff88843fd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdf8115e000 CR3: 0000000357256000 CR4: 00000000003506e0
Call Trace:
<TASK>
xfs_iomap_prealloc_size.constprop.0.isra.0+0x1a6/0x410 [xfs 619a268fb2406d68bd34e007a816b27e70abc22c]
xfs_buffered_write_iomap_begin+0xa87/0xc60 [xfs 619a268fb2406d68bd34e007a816b27e70abc22c]
iomap_iter+0x132/0x2f0
iomap_file_buffered_write+0x92/0x330
xfs_file_buffered_write+0xb1/0x330 [xfs 619a268fb2406d68bd34e007a816b27e70abc22c]
vfs_write+0x2eb/0x410
ksys_write+0x65/0xe0
do_syscall_64+0x2b/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

Found by xfs/538 in alwayscow mode, but this doesn't seem particular to
that test.

Fixes: 590b16516ef3 ("xfs: refactor xfs_iomap_prealloc_size")
Actually-Fixes: 66ae56a53f0e ("xfs: introduce an always_cow mode")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

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iomap: Rename page_ops to folio_ops

The operations in struct page_ops all operate on folios, so rename
struct page_ops to struct folio_ops.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

iomap: Rename page_ops to folio_ops

The operations in struct page_ops all operate on folios, so rename
struct page_ops to struct folio_ops.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[djwong: port around not removing iomap_valid]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

show more ...

xfs: make xfs_iomap_page_ops static

Shut up the sparse warnings about this variable that isn't referenced
anywhere else.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner

xfs: make xfs_iomap_page_ops static

Shut up the sparse warnings about this variable that isn't referenced
anywhere else.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

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xfs: use dax ops for zero and truncate in fsdax mode

Zero and truncate on a dax file may execute CoW. So use dax ops which
contains end work for CoW.

Link: https://lkml.kernel.org/r/1669908730-131

xfs: use dax ops for zero and truncate in fsdax mode

Zero and truncate on a dax file may execute CoW. So use dax ops which
contains end work for CoW.

Link: https://lkml.kernel.org/r/1669908730-131-1-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

fsdax,xfs: set the shared flag when file extent is shared

If a dax page is shared, mapread at different offsets can also trigger
page fault on same dax page. So, change the flag from "cow" to "shar

fsdax,xfs: set the shared flag when file extent is shared

If a dax page is shared, mapread at different offsets can also trigger
page fault on same dax page. So, change the flag from "cow" to "shared".
And get the shared flag from filesystem when read.

Link: https://lkml.kernel.org/r/1669908538-55-5-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

xfs: Remove duplicated include in xfs_iomap.c

./fs/xfs/xfs_iomap.c: xfs_error.h is included more than once.
./fs/xfs/xfs_iomap.c: xfs_errortag.h is included more than once.

Link: https://bugzilla.o

xfs: Remove duplicated include in xfs_iomap.c

./fs/xfs/xfs_iomap.c: xfs_error.h is included more than once.
./fs/xfs/xfs_iomap.c: xfs_errortag.h is included more than once.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=3337
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

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xfs: attach dquots to inode before reading data/cow fork mappings

I've been running near-continuous integration testing of online fsck,
and I've noticed that once a day, one of the ARM VMs will fail

xfs: attach dquots to inode before reading data/cow fork mappings

I've been running near-continuous integration testing of online fsck,
and I've noticed that once a day, one of the ARM VMs will fail the test
with out of order records in the data fork.

xfs/804 races fsstress with online scrub (aka scan but do not change
anything), so I think this might be a bug in the core xfs code. This
also only seems to trigger if one runs the test for more than ~6 minutes
via TIME_FACTOR=13 or something.
https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfstests-dev.git/tree/tests/xfs/804?h=djwong-wtf

I added a debugging patch to the kernel to check the data fork extents
after taking the ILOCK, before dropping ILOCK, and before and after each
bmapping operation. So far I've narrowed it down to the delalloc code
inserting a record in the wrong place in the iext tree:

xfs_bmap_add_extent_hole_delay, near line 2691:

case 0:
/*
* New allocation is not contiguous with another
* delayed allocation.
* Insert a new entry.
*/
oldlen = newlen = 0;
xfs_iunlock_check_datafork(ip); <-- ok here
xfs_iext_insert(ip, icur, new, state);
xfs_iunlock_check_datafork(ip); <-- bad here
break;
}

I recorded the state of the data fork mappings and iext cursor state
when a corrupt data fork is detected immediately after the
xfs_bmap_add_extent_hole_delay call in xfs_bmapi_reserve_delalloc:

ino 0x140bb3 func xfs_bmapi_reserve_delalloc line 4164 data fork:
ino 0x140bb3 nr 0x0 nr_real 0x0 offset 0xb9 blockcount 0x1f startblock 0x935de2 state 1
ino 0x140bb3 nr 0x1 nr_real 0x1 offset 0xe6 blockcount 0xa startblock 0xffffffffe0007 state 0
ino 0x140bb3 nr 0x2 nr_real 0x1 offset 0xd8 blockcount 0xe startblock 0x935e01 state 0

Here we see that a delalloc extent was inserted into the wrong position
in the iext leaf, same as all the other times. The extra trace data I
collected are as follows:

ino 0x140bb3 fork 0 oldoff 0xe6 oldlen 0x4 oldprealloc 0x6 isize 0xe6000
ino 0x140bb3 oldgotoff 0xea oldgotstart 0xfffffffffffffffe oldgotcount 0x0 oldgotstate 0
ino 0x140bb3 crapgotoff 0x0 crapgotstart 0x0 crapgotcount 0x0 crapgotstate 0
ino 0x140bb3 freshgotoff 0xd8 freshgotstart 0x935e01 freshgotcount 0xe freshgotstate 0
ino 0x140bb3 nowgotoff 0xe6 nowgotstart 0xffffffffe0007 nowgotcount 0xa nowgotstate 0
ino 0x140bb3 oldicurpos 1 oldleafnr 2 oldleaf 0xfffffc00f0609a00
ino 0x140bb3 crapicurpos 2 crapleafnr 2 crapleaf 0xfffffc00f0609a00
ino 0x140bb3 freshicurpos 1 freshleafnr 2 freshleaf 0xfffffc00f0609a00
ino 0x140bb3 newicurpos 1 newleafnr 3 newleaf 0xfffffc00f0609a00

The first line shows that xfs_bmapi_reserve_delalloc was called with
whichfork=XFS_DATA_FORK, off=0xe6, len=0x4, prealloc=6.

The second line ("oldgot") shows the contents of @got at the beginning
of the call, which are the results of the first iext lookup in
xfs_buffered_write_iomap_begin.

Line 3 ("crapgot") is the result of duplicating the cursor at the start
of the body of xfs_bmapi_reserve_delalloc and performing a fresh lookup
at @off.

Line 4 ("freshgot") is the result of a new xfs_iext_get_extent right
before the call to xfs_bmap_add_extent_hole_delay. Totally garbage.

Line 5 ("nowgot") is contents of @got after the
xfs_bmap_add_extent_hole_delay call.

Line 6 is the contents of @icur at the beginning fo the call. Lines 7-9
are the contents of the iext cursors at the point where the block
mappings were sampled.

I think @oldgot is a HOLESTARTBLOCK extent because the first lookup
didn't find anything, so we filled in imap with "fake hole until the
end". At the time of the first lookup, I suspect that there's only one
32-block unwritten extent in the mapping (hence oldicurpos==1) but by
the time we get to recording crapgot, crapicurpos==2.

Dave then added:

Ok, that's much simpler to reason about, and implies the smoke is
coming from xfs_buffered_write_iomap_begin() or
xfs_bmapi_reserve_delalloc(). I suspect the former - it does a lot
of stuff with the ILOCK_EXCL held.....

.... including calling xfs_qm_dqattach_locked().

xfs_buffered_write_iomap_begin
ILOCK_EXCL
look up icur
xfs_qm_dqattach_locked
xfs_qm_dqattach_one
xfs_qm_dqget_inode
dquot cache miss
xfs_iunlock(ip, XFS_ILOCK_EXCL);
error = xfs_qm_dqread(mp, id, type, can_alloc, &dqp);
xfs_ilock(ip, XFS_ILOCK_EXCL);
....
xfs_bmapi_reserve_delalloc(icur)

Yup, that's what is letting the magic smoke out -
xfs_qm_dqattach_locked() can cycle the ILOCK. If that happens, we
can pass a stale icur to xfs_bmapi_reserve_delalloc() and it all
goes downhill from there.

Back to Darrick now:

So. Fix this by moving the dqattach_locked call up before we take the
ILOCK, like all the other callers in that file.

Fixes: a526c85c2236 ("xfs: move xfs_file_iomap_begin_delay around") # goes further back than this
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

show more ...

xfs: add debug knob to slow down write for fun

Add a new error injection knob so that we can arbitrarily slow down
pagecache writes to test for race conditions and aberrant reclaim
behavior if the w

xfs: add debug knob to slow down write for fun

Add a new error injection knob so that we can arbitrarily slow down
pagecache writes to test for race conditions and aberrant reclaim
behavior if the writeback mechanisms are slow to issue writeback. This
will enable functional testing for the ifork sequence counters
introduced in commit 304a68b9c63b ("xfs: use iomap_valid method to
detect stale cached iomaps") that fixes write racing with reclaim
writeback.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

show more ...

xfs: drop write error injection is unfixable, remove it

With the changes to scan the page cache for dirty data to avoid data
corruptions from partial write cleanup racing with other page cache
opera

xfs: drop write error injection is unfixable, remove it

With the changes to scan the page cache for dirty data to avoid data
corruptions from partial write cleanup racing with other page cache
operations, the drop writes error injection no longer works the same
way it used to and causes xfs/196 to fail. This is because xfs/196
writes to the file and populates the page cache before it turns on
the error injection and starts failing -overwrites-.

The result is that the original drop-writes code failed writes only
-after- overwriting the data in the cache, followed by invalidates
the cached data, then punching out the delalloc extent from under
that data.

On the surface, this looks fine. The problem is that page cache
invalidation *doesn't guarantee that it removes anything from the
page cache* and it doesn't change the dirty state of the folio. When
block size == page size and we do page aligned IO (as xfs/196 does)
everything happens to align perfectly and page cache invalidation
removes the single page folios that span the written data. Hence the
followup delalloc punch pass does not find cached data over that
range and it can punch the extent out.

IOWs, xfs/196 "works" for block size == page size with the new
code. I say "works", because it actually only works for the case
where IO is page aligned, and no data was read from disk before
writes occur. Because the moment we actually read data first, the
readahead code allocates multipage folios and suddenly the
invalidate code goes back to zeroing subfolio ranges without
changing dirty state.

Hence, with multipage folios in play, block size == page size is
functionally identical to block size < page size behaviour, and
drop-writes is manifestly broken w.r.t to this case. Invalidation of
a subfolio range doesn't result in the folio being removed from the
cache, just the range gets zeroed. Hence after we've sequentially
walked over a folio that we've dirtied (via write data) and then
invalidated, we end up with a dirty folio full of zeroed data.

And because the new code skips punching ranges that have dirty
folios covering them, we end up leaving the delalloc range intact
after failing all the writes. Hence failed writes now end up
writing zeroes to disk in the cases where invalidation zeroes folios
rather than removing them from cache.

This is a fundamental change of behaviour that is needed to avoid
the data corruption vectors that exist in the old write fail path,
and it renders the drop-writes injection non-functional and
unworkable as it stands.

As it is, I think the error injection is also now unnecessary, as
partial writes that need delalloc extent are going to be a lot more
common with stale iomap detection in place. Hence this patch removes
the drop-writes error injection completely. xfs/196 can remain for
testing kernels that don't have this data corruption fix, but those
that do will report:

xfs/196 3s ... [not run] XFS error injection drop_writes unknown on this kernel.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

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xfs: use iomap_valid method to detect stale cached iomaps

Now that iomap supports a mechanism to validate cached iomaps for
buffered write operations, hook it up to the XFS buffered write ops
so tha

xfs: use iomap_valid method to detect stale cached iomaps

Now that iomap supports a mechanism to validate cached iomaps for
buffered write operations, hook it up to the XFS buffered write ops
so that we can avoid data corruptions that result from stale cached
iomaps. See:

https://lore.kernel.org/linux-xfs/20220817093627.GZ3600936@dread.disaster.area/

or the ->iomap_valid() introduction commit for exact details of the
corruption vector.

The validity cookie we store in the iomap is based on the type of
iomap we return. It is expected that the iomap->flags we set in
xfs_bmbt_to_iomap() is not perturbed by the iomap core and are
returned to us in the iomap passed via the .iomap_valid() callback.
This ensures that the validity cookie is always checking the correct
inode fork sequence numbers to detect potential changes that affect
the extent cached by the iomap.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

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xfs: xfs_bmap_punch_delalloc_range() should take a byte range

All the callers of xfs_bmap_punch_delalloc_range() jump through
hoops to convert a byte range to filesystem blocks before calling
xfs_bm

xfs: xfs_bmap_punch_delalloc_range() should take a byte range

All the callers of xfs_bmap_punch_delalloc_range() jump through
hoops to convert a byte range to filesystem blocks before calling
xfs_bmap_punch_delalloc_range(). Instead, pass the byte range to
xfs_bmap_punch_delalloc_range() and have it do the conversion to
filesystem blocks internally.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

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xfs,iomap: move delalloc punching to iomap

Because that's what Christoph wants for this error handling path
only XFS uses.

It requires a new iomap export for handling errors over delalloc
ranges. T

xfs,iomap: move delalloc punching to iomap

Because that's what Christoph wants for this error handling path
only XFS uses.

It requires a new iomap export for handling errors over delalloc
ranges. This is basically the XFS code as is stands, but even though
Christoph wants this as iomap funcitonality, we still have
to call it from the filesystem specific ->iomap_end callback, and
call into the iomap code with yet another filesystem specific
callback to punch the delalloc extent within the defined ranges.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

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xfs: use byte ranges for write cleanup ranges

xfs_buffered_write_iomap_end() currently converts the byte ranges
passed to it to filesystem blocks to pass them to the bmap code to
punch out delalloc

xfs: use byte ranges for write cleanup ranges

xfs_buffered_write_iomap_end() currently converts the byte ranges
passed to it to filesystem blocks to pass them to the bmap code to
punch out delalloc blocks, but then has to convert filesytem
blocks back to byte ranges for page cache truncate.

We're about to make the page cache truncate go away and replace it
with a page cache walk, so having to convert everything to/from/to
filesystem blocks is messy and error-prone. It is much easier to
pass around byte ranges and convert to page indexes and/or
filesystem blocks only where those units are needed.

In preparation for the page cache walk being added, add a helper
that converts byte ranges to filesystem blocks and calls
xfs_bmap_punch_delalloc_range() and convert
xfs_buffered_write_iomap_end() to calculate limits in byte ranges.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

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xfs: punching delalloc extents on write failure is racy

xfs_buffered_write_iomap_end() has a comment about the safety of
punching delalloc extents based holding the IOLOCK_EXCL. This
comment is wron

xfs: punching delalloc extents on write failure is racy

xfs_buffered_write_iomap_end() has a comment about the safety of
punching delalloc extents based holding the IOLOCK_EXCL. This
comment is wrong, and punching delalloc extents is not race free.

When we punch out a delalloc extent after a write failure in
xfs_buffered_write_iomap_end(), we punch out the page cache with
truncate_pagecache_range() before we punch out the delalloc extents.
At this point, we only hold the IOLOCK_EXCL, so there is nothing
stopping mmap() write faults racing with this cleanup operation,
reinstantiating a folio over the range we are about to punch and
hence requiring the delalloc extent to be kept.

If this race condition is hit, we can end up with a dirty page in
the page cache that has no delalloc extent or space reservation
backing it. This leads to bad things happening at writeback time.

To avoid this race condition, we need the page cache truncation to
be atomic w.r.t. the extent manipulation. We can do this by holding
the mapping->invalidate_lock exclusively across this operation -
this will prevent new pages from being inserted into the page cache
whilst we are removing the pages and the backing extent and space
reservation.

Taking the mapping->invalidate_lock exclusively in the buffered
write IO path is safe - it naturally nests inside the IOLOCK (see
truncate and fallocate paths). iomap_zero_range() can be called from
under the mapping->invalidate_lock (from the truncate path via
either xfs_zero_eof() or xfs_truncate_page(), but iomap_zero_iter()
will not instantiate new delalloc pages (because it skips holes) and
hence will not ever need to punch out delalloc extents on failure.

Fix the locking issue, and clean up the code logic a little to avoid
unnecessary work if we didn't allocate the delalloc extent or wrote
the entire region we allocated.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

show more ...

xfs: write page faults in iomap are not buffered writes

When we reserve a delalloc region in xfs_buffered_write_iomap_begin,
we mark the iomap as IOMAP_F_NEW so that the the write context
understand

xfs: write page faults in iomap are not buffered writes

When we reserve a delalloc region in xfs_buffered_write_iomap_begin,
we mark the iomap as IOMAP_F_NEW so that the the write context
understands that it allocated the delalloc region.

If we then fail that buffered write, xfs_buffered_write_iomap_end()
checks for the IOMAP_F_NEW flag and if it is set, it punches out
the unused delalloc region that was allocated for the write.

The assumption this code makes is that all buffered write operations
that can allocate space are run under an exclusive lock (i_rwsem).
This is an invalid assumption: page faults in mmap()d regions call
through this same function pair to map the file range being faulted
and this runs only holding the inode->i_mapping->invalidate_lock in
shared mode.

IOWs, we can have races between page faults and write() calls that
fail the nested page cache write operation that result in data loss.
That is, the failing iomap_end call will punch out the data that
the other racing iomap iteration brought into the page cache. This
can be reproduced with generic/34[46] if we arbitrarily fail page
cache copy-in operations from write() syscalls.

Code analysis tells us that the iomap_page_mkwrite() function holds
the already instantiated and uptodate folio locked across the iomap
mapping iterations. Hence the folio cannot be removed from memory
whilst we are mapping the range it covers, and as such we do not
care if the mapping changes state underneath the iomap iteration
loop:

1. if the folio is not already dirty, there is no writeback races
possible.
2. if we allocated the mapping (delalloc or unwritten), the folio
cannot already be dirty. See #1.
3. If the folio is already dirty, it must be up to date. As we hold
it locked, it cannot be reclaimed from memory. Hence we always
have valid data in the page cache while iterating the mapping.
4. Valid data in the page cache can exist when the underlying
mapping is DELALLOC, UNWRITTEN or WRITTEN. Having the mapping
change from DELALLOC->UNWRITTEN or UNWRITTEN->WRITTEN does not
change the data in the page - it only affects actions if we are
initialising a new page. Hence #3 applies and we don't care
about these extent map transitions racing with
iomap_page_mkwrite().
5. iomap_page_mkwrite() checks for page invalidation races
(truncate, hole punch, etc) after it locks the folio. We also
hold the mapping->invalidation_lock here, and hence the mapping
cannot change due to extent removal operations while we are
iterating the folio.

As such, filesystems that don't use bufferheads will never fail
the iomap_folio_mkwrite_iter() operation on the current mapping,
regardless of whether the iomap should be considered stale.

Further, the range we are asked to iterate is limited to the range
inside EOF that the folio spans. Hence, for XFS, we will only map
the exact range we are asked for, and we will only do speculative
preallocation with delalloc if we are mapping a hole at the EOF
page. The iterator will consume the entire range of the folio that
is within EOF, and anything beyond the EOF block cannot be accessed.
We never need to truncate this post-EOF speculative prealloc away in
the context of the iomap_page_mkwrite() iterator because if it
remains unused we'll remove it when the last reference to the inode
goes away.

Hence we don't actually need an .iomap_end() cleanup/error handling
path at all for iomap_page_mkwrite() for XFS. This means we can
separate the page fault processing from the complexity of the
.iomap_end() processing in the buffered write path. This also means
that the buffered write path will also be able to take the
mapping->invalidate_lock as necessary.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

show more ...

xfs: Add async buffered write support

This adds the async buffered write support to XFS. For async buffered
write requests, the request will return -EAGAIN if the ilock cannot be
obtained immediatel

xfs: Add async buffered write support

This adds the async buffered write support to XFS. For async buffered
write requests, the request will return -EAGAIN if the ilock cannot be
obtained immediately.

Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20220623175157.1715274-15-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

xfs: Specify lockmode when calling xfs_ilock_for_iomap()

This patch changes the helper function xfs_ilock_for_iomap such that the
lock mode must be passed in.

Signed-off-by: Stefan Roesch <shr@fb.c

xfs: Specify lockmode when calling xfs_ilock_for_iomap()

This patch changes the helper function xfs_ilock_for_iomap such that the
lock mode must be passed in.

Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20220623175157.1715274-14-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

xfs: support CoW in fsdax mode

In fsdax mode, WRITE and ZERO on a shared extent need CoW performed.
After that, new allocated extents needs to be remapped to the file. So,
add a CoW identification

xfs: support CoW in fsdax mode

In fsdax mode, WRITE and ZERO on a shared extent need CoW performed.
After that, new allocated extents needs to be remapped to the file. So,
add a CoW identification in ->iomap_begin(), and implement ->iomap_end()
to do the remapping work.

[akpm@linux-foundation.org: make xfs_dax_fault() static]
Link: https://lkml.kernel.org/r/20220603053738.1218681-14-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

xfs: replace XFS_IFORK_Q with a proper predicate function

Replace this shouty macro with a real C function that has a more
descriptive name.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Revie

xfs: replace XFS_IFORK_Q with a proper predicate function

Replace this shouty macro with a real C function that has a more
descriptive name.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

show more ...

xfs: make inode attribute forks a permanent part of struct xfs_inode

Syzkaller reported a UAF bug a while back:

==================================================================
BUG: KASAN: use-af

xfs: make inode attribute forks a permanent part of struct xfs_inode

Syzkaller reported a UAF bug a while back:

==================================================================
BUG: KASAN: use-after-free in xfs_ilock_attr_map_shared+0xe3/0xf6 fs/xfs/xfs_inode.c:127
Read of size 4 at addr ffff88802cec919c by task syz-executor262/2958

CPU: 2 PID: 2958 Comm: syz-executor262 Not tainted
5.15.0-0.30.3-20220406_1406 #3
Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7860+a7792d29
04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x82/0xa9 lib/dump_stack.c:106
print_address_description.constprop.9+0x21/0x2d5 mm/kasan/report.c:256
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold.14+0x7f/0x11b mm/kasan/report.c:459
xfs_ilock_attr_map_shared+0xe3/0xf6 fs/xfs/xfs_inode.c:127
xfs_attr_get+0x378/0x4c2 fs/xfs/libxfs/xfs_attr.c:159
xfs_xattr_get+0xe3/0x150 fs/xfs/xfs_xattr.c:36
__vfs_getxattr+0xdf/0x13d fs/xattr.c:399
cap_inode_need_killpriv+0x41/0x5d security/commoncap.c:300
security_inode_need_killpriv+0x4c/0x97 security/security.c:1408
dentry_needs_remove_privs.part.28+0x21/0x63 fs/inode.c:1912
dentry_needs_remove_privs+0x80/0x9e fs/inode.c:1908
do_truncate+0xc3/0x1e0 fs/open.c:56
handle_truncate fs/namei.c:3084 [inline]
do_open fs/namei.c:3432 [inline]
path_openat+0x30ab/0x396d fs/namei.c:3561
do_filp_open+0x1c4/0x290 fs/namei.c:3588
do_sys_openat2+0x60d/0x98c fs/open.c:1212
do_sys_open+0xcf/0x13c fs/open.c:1228
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3a/0x7e arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0x0
RIP: 0033:0x7f7ef4bb753d
Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48
89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73
01 c3 48 8b 0d 1b 79 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007f7ef52c2ed8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000000000404148 RCX: 00007f7ef4bb753d
RDX: 00007f7ef4bb753d RSI: 0000000000000000 RDI: 0000000020004fc0
RBP: 0000000000404140 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 00007ffd794db37f R14: 00007ffd794db470 R15: 00007f7ef52c2fc0
</TASK>

Allocated by task 2953:
kasan_save_stack+0x19/0x38 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
__kasan_slab_alloc+0x68/0x7c mm/kasan/common.c:467
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook mm/slab.h:519 [inline]
slab_alloc_node mm/slub.c:3213 [inline]
slab_alloc mm/slub.c:3221 [inline]
kmem_cache_alloc+0x11b/0x3eb mm/slub.c:3226
kmem_cache_zalloc include/linux/slab.h:711 [inline]
xfs_ifork_alloc+0x25/0xa2 fs/xfs/libxfs/xfs_inode_fork.c:287
xfs_bmap_add_attrfork+0x3f2/0x9b1 fs/xfs/libxfs/xfs_bmap.c:1098
xfs_attr_set+0xe38/0x12a7 fs/xfs/libxfs/xfs_attr.c:746
xfs_xattr_set+0xeb/0x1a9 fs/xfs/xfs_xattr.c:59
__vfs_setxattr+0x11b/0x177 fs/xattr.c:180
__vfs_setxattr_noperm+0x128/0x5e0 fs/xattr.c:214
__vfs_setxattr_locked+0x1d4/0x258 fs/xattr.c:275
vfs_setxattr+0x154/0x33d fs/xattr.c:301
setxattr+0x216/0x29f fs/xattr.c:575
__do_sys_fsetxattr fs/xattr.c:632 [inline]
__se_sys_fsetxattr fs/xattr.c:621 [inline]
__x64_sys_fsetxattr+0x243/0x2fe fs/xattr.c:621
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3a/0x7e arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0x0

Freed by task 2949:
kasan_save_stack+0x19/0x38 mm/kasan/common.c:38
kasan_set_track+0x1c/0x21 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free mm/kasan/common.c:328 [inline]
__kasan_slab_free+0xe2/0x10e mm/kasan/common.c:374
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1700 [inline]
slab_free_freelist_hook mm/slub.c:1726 [inline]
slab_free mm/slub.c:3492 [inline]
kmem_cache_free+0xdc/0x3ce mm/slub.c:3508
xfs_attr_fork_remove+0x8d/0x132 fs/xfs/libxfs/xfs_attr_leaf.c:773
xfs_attr_sf_removename+0x5dd/0x6cb fs/xfs/libxfs/xfs_attr_leaf.c:822
xfs_attr_remove_iter+0x68c/0x805 fs/xfs/libxfs/xfs_attr.c:1413
xfs_attr_remove_args+0xb1/0x10d fs/xfs/libxfs/xfs_attr.c:684
xfs_attr_set+0xf1e/0x12a7 fs/xfs/libxfs/xfs_attr.c:802
xfs_xattr_set+0xeb/0x1a9 fs/xfs/xfs_xattr.c:59
__vfs_removexattr+0x106/0x16a fs/xattr.c:468
cap_inode_killpriv+0x24/0x47 security/commoncap.c:324
security_inode_killpriv+0x54/0xa1 security/security.c:1414
setattr_prepare+0x1a6/0x897 fs/attr.c:146
xfs_vn_change_ok+0x111/0x15e fs/xfs/xfs_iops.c:682
xfs_vn_setattr_size+0x5f/0x15a fs/xfs/xfs_iops.c:1065
xfs_vn_setattr+0x125/0x2ad fs/xfs/xfs_iops.c:1093
notify_change+0xae5/0x10a1 fs/attr.c:410
do_truncate+0x134/0x1e0 fs/open.c:64
handle_truncate fs/namei.c:3084 [inline]
do_open fs/namei.c:3432 [inline]
path_openat+0x30ab/0x396d fs/namei.c:3561
do_filp_open+0x1c4/0x290 fs/namei.c:3588
do_sys_openat2+0x60d/0x98c fs/open.c:1212
do_sys_open+0xcf/0x13c fs/open.c:1228
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3a/0x7e arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0x0

The buggy address belongs to the object at ffff88802cec9188
which belongs to the cache xfs_ifork of size 40
The buggy address is located 20 bytes inside of
40-byte region [ffff88802cec9188, ffff88802cec91b0)
The buggy address belongs to the page:
page:00000000c3af36a1 refcount:1 mapcount:0 mapping:0000000000000000
index:0x0 pfn:0x2cec9
flags: 0xfffffc0000200(slab|node=0|zone=1|lastcpupid=0x1fffff)
raw: 000fffffc0000200 ffffea00009d2580 0000000600000006 ffff88801a9ffc80
raw: 0000000000000000 0000000080490049 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88802cec9080: fb fb fb fc fc fa fb fb fb fb fc fc fb fb fb fb
ffff88802cec9100: fb fc fc fb fb fb fb fb fc fc fb fb fb fb fb fc
>ffff88802cec9180: fc fa fb fb fb fb fc fc fa fb fb fb fb fc fc fb
^
ffff88802cec9200: fb fb fb fb fc fc fb fb fb fb fb fc fc fb fb fb
ffff88802cec9280: fb fb fc fc fa fb fb fb fb fc fc fa fb fb fb fb
==================================================================

The root cause of this bug is the unlocked access to xfs_inode.i_afp
from the getxattr code paths while trying to determine which ILOCK mode
to use to stabilize the xattr data. Unfortunately, the VFS does not
acquire i_rwsem when vfs_getxattr (or listxattr) call into the
filesystem, which means that getxattr can race with a removexattr that's
tearing down the attr fork and crash:

xfs_attr_set: xfs_attr_get:
xfs_attr_fork_remove: xfs_ilock_attr_map_shared:

xfs_idestroy_fork(ip->i_afp);
kmem_cache_free(xfs_ifork_cache, ip->i_afp);

if (ip->i_afp &&

ip->i_afp = NULL;

xfs_need_iread_extents(ip->i_afp))
<KABOOM>

ip->i_forkoff = 0;

Regrettably, the VFS is much more lax about i_rwsem and getxattr than
is immediately obvious -- not only does it not guarantee that we hold
i_rwsem, it actually doesn't guarantee that we *don't* hold it either.
The getxattr system call won't acquire the lock before calling XFS, but
the file capabilities code calls getxattr with and without i_rwsem held
to determine if the "security.capabilities" xattr is set on the file.

Fixing the VFS locking requires a treewide investigation into every code
path that could touch an xattr and what i_rwsem state it expects or sets
up. That could take years or even prove impossible; fortunately, we
can fix this UAF problem inside XFS.

An earlier version of this patch used smp_wmb in xfs_attr_fork_remove to
ensure that i_forkoff is always zeroed before i_afp is set to null and
changed the read paths to use smp_rmb before accessing i_forkoff and
i_afp, which avoided these UAF problems. However, the patch author was
too busy dealing with other problems in the meantime, and by the time he
came back to this issue, the situation had changed a bit.

On a modern system with selinux, each inode will always have at least
one xattr for the selinux label, so it doesn't make much sense to keep
incurring the extra pointer dereference. Furthermore, Allison's
upcoming parent pointer patchset will also cause nearly every inode in
the filesystem to have extended attributes. Therefore, make the inode
attribute fork structure part of struct xfs_inode, at a cost of 40 more
bytes.

This patch adds a clunky if_present field where necessary to maintain
the existing logic of xattr fork null pointer testing in the existing
codebase. The next patch switches the logic over to XFS_IFORK_Q and it
all goes away.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

show more ...

xfs: convert XFS_IFORK_PTR to a static inline helper

We're about to make this logic do a bit more, so convert the macro to a
static inline function for better typechecking and fewer shouty macros.
N

xfs: convert XFS_IFORK_PTR to a static inline helper

We're about to make this logic do a bit more, so convert the macro to a
static inline function for better typechecking and fewer shouty macros.
No functional changes here.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

show more ...

xfs: Conditionally upgrade existing inodes to use large extent counters

This commit enables upgrading existing inodes to use large extent counters
provided that underlying filesystem's superblock ha

xfs: Conditionally upgrade existing inodes to use large extent counters

This commit enables upgrading existing inodes to use large extent counters
provided that underlying filesystem's superblock has large extent counter
feature enabled.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>

show more ...

xfs: Define max extent length based on on-disk format definition

The maximum extent length depends on maximum block count that can be stored in
a BMBT record. Hence this commit defines MAXEXTLEN bas

xfs: Define max extent length based on on-disk format definition

The maximum extent length depends on maximum block count that can be stored in
a BMBT record. Hence this commit defines MAXEXTLEN based on
BMBT_BLOCKCOUNT_BITLEN.

While at it, the commit also renames MAXEXTLEN to XFS_MAX_BMBT_EXTLEN.

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>

show more ...

fsdax: shift partition offset handling into the file systems

Remove the last user of ->bdev in dax.c by requiring the file system to
pass in an address that already includes the DAX offset. As part

fsdax: shift partition offset handling into the file systems

Remove the last user of ->bdev in dax.c by requiring the file system to
pass in an address that already includes the DAX offset. As part of the
only set ->bdev or ->daxdev when actually required in the ->iomap_begin
methods.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com> [erofs]
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20211129102203.2243509-27-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

show more ...