Commit Graph

19 Commits

Author SHA1 Message Date
Andreas Gruenbacher
c114bbc6c4 iomap: Fix direct I/O write consistency check
When a direct I/O write falls back to buffered I/O entirely, dio->size
will be 0 in iomap_dio_complete.  Function invalidate_inode_pages2_range
will try to invalidate the rest of the address space.  If there are any
dirty pages in that range, the write will fail and a "Page cache
invalidation failure on direct I/O" error will be logged.

On gfs2, this can be reproduced as follows:

  xfs_io \
    -c "open -ft foo" -c "pwrite 4k 4k" -c "close" \
    -c "open -d foo" -c "pwrite 0 4k"

Fix this by recognizing 0-length writes.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2020-09-10 08:26:16 -07:00
Qian Cai
a805c11165 iomap: fix WARN_ON_ONCE() from unprivileged users
It is trivial to trigger a WARN_ON_ONCE(1) in iomap_dio_actor() by
unprivileged users which would taint the kernel, or worse - panic if
panic_on_warn or panic_on_taint is set. Hence, just convert it to
pr_warn_ratelimited() to let users know their workloads are racing.
Thank Dave Chinner for the initial analysis of the racing reproducers.

Signed-off-by: Qian Cai <cai@lca.pw>
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>
2020-09-10 08:26:15 -07:00
Christoph Hellwig
60263d5889 iomap: fall back to buffered writes for invalidation failures
Failing to invalid the page cache means data in incoherent, which is
a very bad state for the system.  Always fall back to buffered I/O
through the page cache if we can't invalidate mappings.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu> # for ext4
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com> # for gfs2
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
2020-08-05 09:24:16 -07:00
Dave Chinner
54752de928 iomap: Only invalidate page cache pages on direct IO writes
The historic requirement for XFS to invalidate cached pages on
direct IO reads has been lost in the twisty pages of history - it was
inherited from Irix, which implemented page cache invalidation on
read as a method of working around problems synchronising page
cache state with uncached IO.

XFS has carried this ever since. In the initial linux ports it was
necessary to get mmap and DIO to play "ok" together and not
immediately corrupt data. This was the state of play until the linux
kernel had infrastructure to track unwritten extents and synchronise
page faults with allocations and unwritten extent conversions
(->page_mkwrite infrastructure). IOws, the page cache invalidation
on DIO read was necessary to prevent trivial data corruptions. This
didn't solve all the problems, though.

There were peformance problems if we didn't invalidate the entire
page cache over the file on read - we couldn't easily determine if
the cached pages were over the range of the IO, and invalidation
required taking a serialising lock (i_mutex) on the inode. This
serialising lock was an issue for XFS, as it was the only exclusive
lock in the direct Io read path.

Hence if there were any cached pages, we'd just invalidate the
entire file in one go so that subsequent IOs didn't need to take the
serialising lock. This was a problem that prevented ranged
invalidation from being particularly useful for avoiding the
remaining coherency issues. This was solved with the conversion of
i_mutex to i_rwsem and the conversion of the XFS inode IO lock to
use i_rwsem. Hence we could now just do ranged invalidation and the
performance problem went away.

However, page cache invalidation was still needed to serialise
sub-page/sub-block zeroing via direct IO against buffered IO because
bufferhead state attached to the cached page could get out of whack
when direct IOs were issued.  We've removed bufferheads from the
XFS code, and we don't carry any extent state on the cached pages
anymore, and so this problem has gone away, too.

IOWs, it would appear that we don't have any good reason to be
invalidating the page cache on DIO reads anymore. Hence remove the
invalidation on read because it is unnecessary overhead,
not needed to maintain coherency between mmap/buffered access and
direct IO anymore, and prevents anyone from using direct IO reads
from intentionally invalidating the page cache of a file.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-08-05 09:24:16 -07:00
Linus Torvalds
f3cdc8ae11 for-5.8-tag
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Merge tag 'for-5.8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs updates from David Sterba:
 "Highlights:

   - speedup dead root detection during orphan cleanup, eg. when there
     are many deleted subvolumes waiting to be cleaned, the trees are
     now looked up in radix tree instead of a O(N^2) search

   - snapshot creation with inherited qgroup will mark the qgroup
     inconsistent, requires a rescan

   - send will emit file capabilities after chown, this produces a
     stream that does not need postprocessing to set the capabilities
     again

   - direct io ported to iomap infrastructure, cleaned up and simplified
     code, notably removing last use of struct buffer_head in btrfs code

  Core changes:

   - factor out backreference iteration, to be used by ordinary
     backreferences and relocation code

   - improved global block reserve utilization
      * better logic to serialize requests
      * increased maximum available for unlink
      * improved handling on large pages (64K)

   - direct io cleanups and fixes
      * simplify layering, where cloned bios were unnecessarily created
        for some cases
      * error handling fixes (submit, endio)
      * remove repair worker thread, used to avoid deadlocks during
        repair

   - refactored block group reading code, preparatory work for new type
     of block group storage that should improve mount time on large
     filesystems

  Cleanups:

   - cleaned up (and slightly sped up) set/get helpers for metadata data
     structure members

   - root bit REF_COWS got renamed to SHAREABLE to reflect the that the
     blocks of the tree get shared either among subvolumes or with the
     relocation trees

  Fixes:

   - when subvolume deletion fails due to ENOSPC, the filesystem is not
     turned read-only

   - device scan deals with devices from other filesystems that changed
     ownership due to overwrite (mkfs)

   - fix a race between scrub and block group removal/allocation

   - fix long standing bug of a runaway balance operation, printing the
     same line to the syslog, caused by a stale status bit on a reloc
     tree that prevented progress

   - fix corrupt log due to concurrent fsync of inodes with shared
     extents

   - fix space underflow for NODATACOW and buffered writes when it for
     some reason needs to fallback to COW mode"

* tag 'for-5.8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (133 commits)
  btrfs: fix space_info bytes_may_use underflow during space cache writeout
  btrfs: fix space_info bytes_may_use underflow after nocow buffered write
  btrfs: fix wrong file range cleanup after an error filling dealloc range
  btrfs: remove redundant local variable in read_block_for_search
  btrfs: open code key_search
  btrfs: split btrfs_direct_IO to read and write part
  btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK
  fs: remove dio_end_io()
  btrfs: switch to iomap_dio_rw() for dio
  iomap: remove lockdep_assert_held()
  iomap: add a filesystem hook for direct I/O bio submission
  fs: export generic_file_buffered_read()
  btrfs: turn space cache writeout failure messages into debug messages
  btrfs: include error on messages about failure to write space/inode caches
  btrfs: remove useless 'fail_unlock' label from btrfs_csum_file_blocks()
  btrfs: do not ignore error from btrfs_next_leaf() when inserting checksums
  btrfs: make checksum item extension more efficient
  btrfs: fix corrupt log due to concurrent fsync of inodes with shared extents
  btrfs: unexport btrfs_compress_set_level()
  btrfs: simplify iget helpers
  ...
2020-06-02 19:59:25 -07:00
Goldwyn Rodrigues
3ad99bec6e iomap: remove lockdep_assert_held()
Filesystems such as btrfs can perform direct I/O without holding the
inode->i_rwsem in some of the cases like writing within i_size.  So,
remove the check for lockdep_assert_held() in iomap_dio_rw().

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-05-25 13:12:53 +02:00
Goldwyn Rodrigues
8cecd0ba85 iomap: add a filesystem hook for direct I/O bio submission
This helps filesystems to perform tasks on the bio while submitting for
I/O. This could be post-write operations such as data CRC or data
replication for fs-handled RAID.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-05-25 13:12:53 +02:00
Ming Lei
e6249cdd46 block: add blk_io_schedule() for avoiding task hung in sync dio
Sync dio could be big, or may take long time in discard or in case of
IO failure.

We have prevented task hung in submit_bio_wait() and blk_execute_rq(),
so apply the same trick for prevent task hung from happening in sync dio.

Add helper of blk_io_schedule() and use io_schedule_timeout() to prevent
task hung warning.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Cc: Salman Qazi <sqazi@google.com>
Cc: Jesse Barnes <jsbarnes@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-12 20:32:42 -06:00
yangerkun
d9973ce2fe iomap: fix comments in iomap_dio_rw
Double 'three' exists in the comments of iomap_dio_rw.

Signed-off-by: yangerkun <yangerkun@huawei.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>
2020-03-18 08:04:36 -07:00
Johannes Thumshirn
88cfd30e18 iomap: remove unneeded variable in iomap_dio_rw()
The 'start' variable indicates the start of a filemap and is set to the
iocb's position, which we have already cached as 'pos', upon function
entry.

'pos' is used as a cursor indicating the current position and updated
later in iomap_dio_rw(), but not before the last use of 'start'.

Remove 'start' as it's synonym for 'pos' before we're entering the loop
calling iomapp_apply().

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
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>
2019-11-26 09:28:47 -08:00
Jan Kara
f550ee9b85 iomap: Do not create fake iter in iomap_dio_bio_actor()
iomap_dio_bio_actor() copies iter to a local variable and then limits it
to a file extent we have mapped. When IO is submitted,
iomap_dio_bio_actor() advances the original iter while the copied iter
is advanced inside bio_iov_iter_get_pages(). This logic is non-obvious
especially because both iters still point to same shared structures
(such as pipe info) so if iov_iter_advance() changes anything in the
shared structure, this scheme breaks. Let's just truncate and reexpand
the original iter as needed instead of playing games with copying iters
and keeping them in sync.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2019-11-26 09:28:47 -08:00
Jan Kara
419e9c38aa iomap: Fix pipe page leakage during splicing
When splicing using iomap_dio_rw() to a pipe, we may leak pipe pages
because bio_iov_iter_get_pages() records that the pipe will have full
extent worth of data however if file size is not block size aligned
iomap_dio_rw() returns less than what bio_iov_iter_get_pages() set up
and splice code gets confused leaking a pipe page with the file tail.

Handle the situation similarly to the old direct IO implementation and
revert iter to actually returned read amount which makes iter consistent
with value returned from iomap_dio_rw() and thus the splice code is
happy.

Fixes: ff6a9292e6 ("iomap: implement direct I/O")
CC: stable@vger.kernel.org
Reported-by: syzbot+991400e8eba7e00a26e1@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2019-11-22 08:36:02 -08:00
Jan Stancek
e9f930ac88 iomap: fix return value of iomap_dio_bio_actor on 32bit systems
Naresh reported LTP diotest4 failing for 32bit x86 and arm -next
kernels on ext4. Same problem exists in 5.4-rc7 on xfs.

The failure comes down to:
  openat(AT_FDCWD, "testdata-4.5918", O_RDWR|O_DIRECT) = 4
  mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f7b000
  read(4, 0xb7f7b000, 4096)              = 0 // expects -EFAULT

Problem is conversion at iomap_dio_bio_actor() return. Ternary
operator has a return type and an attempt is made to convert each
of operands to the type of the other. In this case "ret" (int)
is converted to type of "copied" (unsigned long). Both have size
of 4 bytes:
    size_t copied = 0;
    int ret = -14;
    long long actor_ret = copied ? copied : ret;

    On x86_64: actor_ret == -14;
    On x86   : actor_ret == 4294967282

Replace ternary operator with 2 return statements to avoid this
unwanted conversion.

Fixes: 4721a60109 ("iomap: dio data corruption and spurious errors when pipes fill")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Jan Stancek <jstancek@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>
2019-11-11 12:58:24 -08:00
Joseph Qi
a901004214 fs/iomap: remove redundant check in iomap_dio_rw()
We've already check if it is READ iov_iter, no need check again.

Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2019-10-29 09:51:24 -07:00
Goldwyn Rodrigues
c039b99792 iomap: use a srcmap for a read-modify-write I/O
The srcmap is used to identify where the read is to be performed from.
It is passed to ->iomap_begin, which can fill it in if we need to read
data for partially written blocks from a different location than the
write target.  The srcmap is only supported for buffered writes so far.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
[hch: merged two patches, removed the IOMAP_F_COW flag, use iomap as
      srcmap if not set, adjust length down to srcmap end as well]
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>
Acked-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
2019-10-21 08:51:59 -07:00
Jan Kara
13ef954445 iomap: Allow forcing of waiting for running DIO in iomap_dio_rw()
Filesystems do not support doing IO as asynchronous in some cases. For
example in case of unaligned writes or in case file size needs to be
extended (e.g. for ext4). Instead of forcing filesystem to wait for AIO
in such cases, add argument to iomap_dio_rw() which makes the function
wait for IO completion. This also results in executing
iomap_dio_complete() inline in iomap_dio_rw() providing its return value
to the caller as for ordinary sync IO.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2019-10-15 08:43:42 -07:00
Christoph Hellwig
838c4f3d75 iomap: move the iomap_dio_rw ->end_io callback into a structure
Add a new iomap_dio_ops structure that for now just contains the end_io
handler.  This avoid storing the function pointer in a mutable structure,
which is a possible exploit vector for kernel code execution, and prepares
for adding a submit_io handler that btrfs needs.

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>
2019-09-19 15:32:45 -07:00
Matthew Bobrowski
6fe7b99014 iomap: split size and error for iomap_dio_rw ->end_io
Modify the calling convention for the iomap_dio_rw ->end_io() callback.
Rather than passing either dio->error or dio->size as the 'size' argument,
instead pass both the dio->error and the dio->size value separately.

In the instance that an error occurred during a write, we currently cannot
determine whether any blocks have been allocated beyond the current EOF and
data has subsequently been written to these blocks within the ->end_io()
callback. As a result, we cannot judge whether we should take the truncate
failed write path. Having both dio->error and dio->size will allow us to
perform such checks within this callback.

Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
[hch: minor cleanups]
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>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
2019-09-19 15:32:44 -07:00
Darrick J. Wong
db074436f4 iomap: move the direct IO code into a separate file
Move the direct IO code into a separate file so that we can group
related functions in a single file instead of having a single enormous
source file.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2019-07-17 07:16:00 -07:00