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author | Eryu Guan <eguan@redhat.com> | 2017-10-13 09:47:46 -0700 |
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committer | Darrick J. Wong <darrick.wong@oracle.com> | 2017-10-16 12:11:56 -0700 |
commit | 5e25c269e17de4c5a23ce886cda612b01365a944 (patch) | |
tree | b89ee04551f1160174b58954002a268c3647b927 /fs/iomap.c | |
parent | 793d7dbe6d82a50b9d14bf992b9eaacb70a11ce6 (diff) | |
download | linux-5e25c269e17de4c5a23ce886cda612b01365a944.tar.gz linux-5e25c269e17de4c5a23ce886cda612b01365a944.tar.bz2 linux-5e25c269e17de4c5a23ce886cda612b01365a944.zip |
fs: invalidate page cache after end_io() in dio completion
Commit 332391a9935d ("fs: Fix page cache inconsistency when mixing
buffered and AIO DIO") moved page cache invalidation from
iomap_dio_rw() to iomap_dio_complete() for iomap based direct write
path, but before the dio->end_io() call, and it re-introdued the bug
fixed by commit c771c14baa33 ("iomap: invalidate page caches should
be after iomap_dio_complete() in direct write").
I found this because fstests generic/418 started failing on XFS with
v4.14-rc3 kernel, which is the regression test for this specific
bug.
So similarly, fix it by moving dio->end_io() (which does the
unwritten extent conversion) before page cache invalidation, to make
sure next buffer read reads the final real allocations not unwritten
extents. I also add some comments about why should end_io() go first
in case we get it wrong again in the future.
Note that, there's no such problem in the non-iomap based direct
write path, because we didn't remove the page cache invalidation
after the ->direct_IO() in generic_file_direct_write() call, but I
decided to fix dio_complete() too so we don't leave a landmine
there, also be consistent with iomap_dio_complete().
Fixes: 332391a9935d ("fs: Fix page cache inconsistency when mixing buffered and AIO DIO")
Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Diffstat (limited to 'fs/iomap.c')
-rw-r--r-- | fs/iomap.c | 41 |
1 files changed, 24 insertions, 17 deletions
diff --git a/fs/iomap.c b/fs/iomap.c index be61cf742b5e..d4801f8dd4fd 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -714,23 +714,9 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio) { struct kiocb *iocb = dio->iocb; struct inode *inode = file_inode(iocb->ki_filp); + loff_t offset = iocb->ki_pos; ssize_t ret; - /* - * Try again to invalidate clean pages which might have been cached by - * non-direct readahead, or faulted in by get_user_pages() if the source - * of the write was an mmap'ed region of the file we're writing. Either - * one is a pretty crazy thing to do, so we don't support it 100%. If - * this invalidation fails, tough, the write still worked... - */ - if (!dio->error && - (dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) { - ret = invalidate_inode_pages2_range(inode->i_mapping, - iocb->ki_pos >> PAGE_SHIFT, - (iocb->ki_pos + dio->size - 1) >> PAGE_SHIFT); - WARN_ON_ONCE(ret); - } - if (dio->end_io) { ret = dio->end_io(iocb, dio->error ? dio->error : dio->size, @@ -742,12 +728,33 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio) if (likely(!ret)) { ret = dio->size; /* check for short read */ - if (iocb->ki_pos + ret > dio->i_size && + if (offset + ret > dio->i_size && !(dio->flags & IOMAP_DIO_WRITE)) - ret = dio->i_size - iocb->ki_pos; + ret = dio->i_size - offset; iocb->ki_pos += ret; } + /* + * Try again to invalidate clean pages which might have been cached by + * non-direct readahead, or faulted in by get_user_pages() if the source + * of the write was an mmap'ed region of the file we're writing. Either + * one is a pretty crazy thing to do, so we don't support it 100%. If + * this invalidation fails, tough, the write still worked... + * + * And this page cache invalidation has to be after dio->end_io(), as + * some filesystems convert unwritten extents to real allocations in + * end_io() when necessary, otherwise a racing buffer read would cache + * zeros from unwritten extents. + */ + if (!dio->error && + (dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) { + int err; + err = invalidate_inode_pages2_range(inode->i_mapping, + offset >> PAGE_SHIFT, + (offset + dio->size - 1) >> PAGE_SHIFT); + WARN_ON_ONCE(err); + } + inode_dio_end(file_inode(iocb->ki_filp)); kfree(dio); |