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btrfs: call iomap_dio_complete() without inode_lock

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If direct writes are called with O_DIRECT | O_DSYNC, it will result in a
deadlock because iomap_dio_rw() is called under i_rwsem which calls:

  iomap_dio_complete()
    generic_write_sync()
      btrfs_sync_file()

btrfs_sync_file() requires i_rwsem, so call __iomap_dio_rw() with the
i_rwsem locked, and call iomap_dio_complete() after unlocking i_rwsem.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues 2020-09-24 11:39:20 -05:00 committed by David Sterba
parent 502756b380
commit a42fa64316
1 changed files with 11 additions and 13 deletions
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24
fs/btrfs/file.c
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@ -1906,6 +1906,7 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
loff_t endbyte;
ssize_t err;
unsigned int ilock_flags = 0;
struct iomap_dio *dio = NULL;
if (iocb->ki_flags & IOCB_NOWAIT)
ilock_flags |= BTRFS_ILOCK_TRY;
@ -1948,22 +1949,19 @@ relock:
goto buffered;
}
/*
* This is actually a sync iocb, so we need our fancy endio to know if
* we need to sync.
*/
if (current->journal_info)
written = iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops,
&btrfs_sync_dops, is_sync_kiocb(iocb));
else
written = iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops,
&btrfs_dio_ops, is_sync_kiocb(iocb));
if (written == -ENOTBLK)
written = 0;
dio = __iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops,
&btrfs_dio_ops, is_sync_kiocb(iocb));
btrfs_inode_unlock(inode, ilock_flags);
if (IS_ERR_OR_NULL(dio)) {
err = PTR_ERR_OR_ZERO(dio);
if (err < 0 && err != -ENOTBLK)
goto out;
} else {
written = iomap_dio_complete(dio);
}
if (written < 0 || !iov_iter_count(from)) {
err = written;
goto out;