diff options
author | David Howells <dhowells@redhat.com> | 2023-10-11 09:29:43 +0100 |
---|---|---|
committer | David Howells <dhowells@redhat.com> | 2023-12-28 09:45:25 +0000 |
commit | 80645bd4aa33a5c325f11b8dc6b38b38410ad5c0 (patch) | |
tree | aa8f717b855218b2b8181dc78733e20268c3ff28 /fs | |
parent | 102a7e2c598c22bd2621fa97eb1c93c89d469a12 (diff) |
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: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Diffstat (limited to 'fs')
-rw-r--r-- | fs/netfs/buffered_read.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index 950f63fc156a..a59e7b2edaac 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -558,3 +558,76 @@ error: _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); |