Commit 80645bd4 authored by David Howells's avatar David Howells
Browse files

netfs: Provide netfs_file_read_iter() 



Provide a top-level-ish function that can be pointed to directly by
->read_iter file op.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
parent 102a7e2c

fs/netfs/buffered_read.c

+73 −0
Original line number Diff line number Diff line
@@ -558,3 +558,76 @@ int netfs_prefetch_for_write(struct file *file, struct folio *folio, 
	_leave(" = %d", ret);

	return ret;

}



/**

 * netfs_buffered_read_iter - Filesystem buffered I/O read routine

 * @iocb: kernel I/O control block

 * @iter: destination for the data read

 *

 * This is the ->read_iter() routine for all filesystems that can use the page

 * cache directly.

 *

 * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall be

 * returned when no data can be read without waiting for I/O requests to

 * complete; it doesn't prevent readahead.

 *

 * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O requests

 * shall be made for the read or for readahead.  When no data can be read,

 * -EAGAIN shall be returned.  When readahead would be triggered, a partial,

 * possibly empty read shall be returned.

 *

 * Return:

 * * number of bytes copied, even for partial reads

 * * negative error code (or 0 if IOCB_NOIO) if nothing was read

 */

ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter)

{

	struct inode *inode = file_inode(iocb->ki_filp);

	struct netfs_inode *ictx = netfs_inode(inode);

	ssize_t ret;



	if (WARN_ON_ONCE((iocb->ki_flags & IOCB_DIRECT) ||

			 test_bit(NETFS_ICTX_UNBUFFERED, &ictx->flags)))

		return -EINVAL;



	ret = netfs_start_io_read(inode);

	if (ret == 0) {

		ret = filemap_read(iocb, iter, 0);

		netfs_end_io_read(inode);

	}

	return ret;

}

EXPORT_SYMBOL(netfs_buffered_read_iter);



/**

 * netfs_file_read_iter - Generic filesystem read routine

 * @iocb: kernel I/O control block

 * @iter: destination for the data read

 *

 * This is the ->read_iter() routine for all filesystems that can use the page

 * cache directly.

 *

 * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall be

 * returned when no data can be read without waiting for I/O requests to

 * complete; it doesn't prevent readahead.

 *

 * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O requests

 * shall be made for the read or for readahead.  When no data can be read,

 * -EAGAIN shall be returned.  When readahead would be triggered, a partial,

 * possibly empty read shall be returned.

 *

 * Return:

 * * number of bytes copied, even for partial reads

 * * negative error code (or 0 if IOCB_NOIO) if nothing was read

 */

ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)

{

	struct netfs_inode *ictx = netfs_inode(iocb->ki_filp->f_mapping->host);



	if ((iocb->ki_flags & IOCB_DIRECT) ||

	    test_bit(NETFS_ICTX_UNBUFFERED, &ictx->flags))

		return netfs_unbuffered_read_iter(iocb, iter);



	return netfs_buffered_read_iter(iocb, iter);

}

EXPORT_SYMBOL(netfs_file_read_iter);

include/linux/netfs.h

+2 −0
Original line number Diff line number Diff line
@@ -378,6 +378,8 @@ struct netfs_cache_ops { 


/* High-level read API. */

ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);

ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);

ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);



/* High-level write API */

ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,