[PATCH 24/64] netfs: Pass more information on how to deal with a hole in the cache
From: David Howells <dhowells@redhat.com>
Date: 2021-11-29 14:31:01
Also in:
ceph-devel, linux-cifs, linux-fsdevel, lkml
Subsystem:
filesystems (vfs and infrastructure), filesystems [netfs library], the rest · Maintainers:
Alexander Viro, Christian Brauner, David Howells, Paulo Alcantara, Linus Torvalds
Pass more information to the cache on how to deal with a hole if it
encounters one when trying to read from the cache. Three options are
provided:
(1) NETFS_READ_HOLE_IGNORE. Read the hole along with the data, assuming
it to be a punched-out extent by the backing filesystem.
(2) NETFS_READ_HOLE_CLEAR. If there's a hole, erase the requested region
of the cache and clear the read buffer.
(3) NETFS_READ_HOLE_FAIL. Fail the read if a hole is detected.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
---
fs/netfs/read_helper.c | 8 ++++----
include/linux/netfs.h | 11 ++++++++++-
2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 7dc79fa8a1f3..08df413efdf3 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c@@ -170,7 +170,7 @@ static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error */ static void netfs_read_from_cache(struct netfs_read_request *rreq, struct netfs_read_subrequest *subreq, - bool seek_data) + enum netfs_read_from_hole read_hole) { struct netfs_cache_resources *cres = &rreq->cache_resources; struct iov_iter iter;
@@ -180,7 +180,7 @@ static void netfs_read_from_cache(struct netfs_read_request *rreq, subreq->start + subreq->transferred, subreq->len - subreq->transferred); - cres->ops->read(cres, subreq->start, &iter, seek_data, + cres->ops->read(cres, subreq->start, &iter, read_hole, netfs_cache_read_terminated, subreq); }
@@ -466,7 +466,7 @@ static void netfs_rreq_short_read(struct netfs_read_request *rreq, netfs_get_read_subrequest(subreq); atomic_inc(&rreq->nr_rd_ops); if (subreq->source == NETFS_READ_FROM_CACHE) - netfs_read_from_cache(rreq, subreq, true); + netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_CLEAR); else netfs_read_from_server(rreq, subreq); }
@@ -794,7 +794,7 @@ static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq, netfs_read_from_server(rreq, subreq); break; case NETFS_READ_FROM_CACHE: - netfs_read_from_cache(rreq, subreq, false); + netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_IGNORE); break; default: BUG();
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 5a46fde65759..b46c39d98bbd 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h@@ -196,6 +196,15 @@ struct netfs_read_request_ops { void (*cleanup)(struct address_space *mapping, void *netfs_priv); }; +/* + * How to handle reading from a hole. + */ +enum netfs_read_from_hole { + NETFS_READ_HOLE_IGNORE, + NETFS_READ_HOLE_CLEAR, + NETFS_READ_HOLE_FAIL, +}; + /* * Table of operations for access to a cache. This is obtained by * rreq->ops->begin_cache_operation().
@@ -208,7 +217,7 @@ struct netfs_cache_ops { int (*read)(struct netfs_cache_resources *cres, loff_t start_pos, struct iov_iter *iter, - bool seek_data, + enum netfs_read_from_hole read_hole, netfs_io_terminated_t term_func, void *term_func_priv);