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@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
Link: https://lore.kernel.org/r/163819612321.215744.9738308885948264476.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1
Link: https://lore.kernel.org/r/163906914460.143852.6284247083607910189.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v2
---
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 9dd76b8914f2..6169659857b3 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);
}
@@ -461,7 +461,7 @@ 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);
}
@@ -789,7 +789,7 @@ 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);
