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Btrfs: wait ordered range before doing direct io 

My recent truncate patch uncovered this bug, but I can reproduce it without the
truncate patch.  If you mount with -o compress-force, do a direct write to some
area, do a buffered write to some other area, and then do a direct read you will
get the wrong data for where you did the buffered write.  This is because the
generic direct io helpers only call filemap_write_and_wait once, and for
compression we need it twice.  So to be safe add the btrfs_wait_ordered_range to
the start of the direct io function to make sure any compressed writes have
truly been written.  This patch makes xfstests 130 pass when you mount with -o
compress-force=lzo.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
wifi-calibration
Josef Bacik 2013-07-02 10:38:02 -04:00
parent 7fb7d76f96
commit 0e267c44c3
1 changed files with 9 additions and 1 deletions
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10
fs/btrfs/inode.c
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@ -7270,8 +7270,16 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
atomic_inc(&inode->i_dio_count);
smp_mb__after_atomic_inc();
/*
* The generic stuff only does filemap_write_and_wait_range, which isn't
* enough if we've written compressed pages to this area, so we need to
* call btrfs_wait_ordered_range to make absolutely sure that any
* outstanding dirty pages are on disk.
*/
count = iov_length(iov, nr_segs);
btrfs_wait_ordered_range(inode, offset, count);
if (rw & WRITE) {
count = iov_length(iov, nr_segs);
/*
* If the write DIO is beyond the EOF, we need update
* the isize, but it is protected by i_mutex. So we can