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direct-io: don't force writeback for reads beyond EOF 

If a DIO read starts past EOF, the kernel won't attempt it, so we don't
need to flush dirty pages before failing the syscall.

Link: https://lore.kernel.org/r/20201008062620.2928326-3-krisman@collabora.com
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Gabriel Krisman Bertazi 2020-10-08 02:26:19 -04:00 committed by Jan Kara
parent 46d716025a
commit 0a9164cb7f
1 changed files with 11 additions and 13 deletions
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24
fs/direct-io.c
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@ -1188,19 +1188,9 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
memset(dio, 0, offsetof(struct dio, pages));
dio->flags = flags;
if (dio->flags & DIO_LOCKING) {
if (iov_iter_rw(iter) == READ) {
struct address_space *mapping =
iocb->ki_filp->f_mapping;
/* will be released by direct_io_worker */
inode_lock(inode);
retval = filemap_write_and_wait_range(mapping, offset,
end - 1);
if (retval)
goto fail_dio;
}
if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) {
/* will be released by direct_io_worker */
inode_lock(inode);
}
/* Once we sampled i_size check for reads beyond EOF */
@ -1210,6 +1200,14 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
goto fail_dio;
}
if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) {
struct address_space *mapping = iocb->ki_filp->f_mapping;
retval = filemap_write_and_wait_range(mapping, offset, end - 1);
if (retval)
goto fail_dio;
}
/*
* For file extending writes updating i_size before data writeouts
* complete can expose uninitialized blocks in dumb filesystems.