diff options
| author | Jan Kara <jack@suse.cz> | 2015-11-30 10:15:42 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-11-30 10:15:42 -0700 |
| commit | 74cedf9b6c603f2278a05bc91b140b32b434d0b5 (patch) | |
| tree | 0d4412cee169295a290867b72545b65c742527a8 /fs/direct-io.c | |
| parent | bf4e6b4e757488dee1b6a581f49c7ac34cd217f8 (diff) | |
| download | lwn-74cedf9b6c603f2278a05bc91b140b32b434d0b5.tar.gz lwn-74cedf9b6c603f2278a05bc91b140b32b434d0b5.zip | |
direct-io: Fix negative return from dio read beyond eof
Assume a filesystem with 4KB blocks. When a file has size 1000 bytes and
we issue direct IO read at offset 1024, blockdev_direct_IO() reads the
tail of the last block and the logic for handling short DIO reads in
dio_complete() results in a return value -24 (1000 - 1024) which
obviously confuses userspace.
Fix the problem by bailing out early once we sample i_size and can
reliably check that direct IO read starts beyond i_size.
Reported-by: Avi Kivity <avi@scylladb.com>
Fixes: 9fe55eea7e4b444bafc42fa0000cc2d1d2847275
CC: stable@vger.kernel.org
CC: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/direct-io.c')
| -rw-r--r-- | fs/direct-io.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index cb5337d8c273..1c75a3a07f8f 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1169,6 +1169,15 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, } } + /* Once we sampled i_size check for reads beyond EOF */ + dio->i_size = i_size_read(inode); + if (iov_iter_rw(iter) == READ && offset >= dio->i_size) { + if (dio->flags & DIO_LOCKING) + mutex_unlock(&inode->i_mutex); + kmem_cache_free(dio_cache, dio); + goto out; + } + /* * For file extending writes updating i_size before data writeouts * complete can expose uninitialized blocks in dumb filesystems. @@ -1222,7 +1231,6 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, sdio.next_block_for_io = -1; dio->iocb = iocb; - dio->i_size = i_size_read(inode); spin_lock_init(&dio->bio_lock); dio->refcount = 1; |