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authorDavid Howells <dhowells@redhat.com>2023-10-11 09:29:43 +0100
committerDavid Howells <dhowells@redhat.com>2023-12-28 09:45:25 +0000
commit80645bd4aa33a5c325f11b8dc6b38b38410ad5c0 (patch)
treeaa8f717b855218b2b8181dc78733e20268c3ff28 /fs
parent102a7e2c598c22bd2621fa97eb1c93c89d469a12 (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.c73
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);