Add prepare_ondemand_read() callback dedicated for the on-demand read
scenario, so that callers from this scenario can be decoupled from
netfs_io_subrequest.
To reuse the hole detecting logic as mush as possible, both the
implementation of prepare_read() and prepare_ondemand_read() inside
Cachefiles call a common routine.
In the near future, prepare_read() will get enhanced and more
information will be needed and then returned to callers. Thus
netfs_io_subrequest is a reasonable candidate for holding places for all
these information needed in the internal implementation.
Signed-off-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
fs/cachefiles/io.c | 42 +++++++++++++++++++++++++------
include/linux/netfs.h | 7 ++++++
include/trace/events/cachefiles.h | 4 +--
3 files changed, 43 insertions(+), 10 deletions(-)
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 000a28f46e59..6427259fcba9 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -385,16 +385,11 @@ static int cachefiles_write(struct netfs_cache_resources *cres,
term_func, term_func_priv);
}
-/*
- * Prepare a read operation, shortening it to a cached/uncached
- * boundary as appropriate.
- */
-static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest *subreq,
- loff_t i_size)
+static enum netfs_io_source cachefiles_do_prepare_read(struct netfs_io_subrequest *subreq,
+ struct netfs_cache_resources *cres,
+ loff_t i_size)
{
enum cachefiles_prepare_read_trace why;
- struct netfs_io_request *rreq = subreq->rreq;
- struct netfs_cache_resources *cres = &rreq->cache_resources;
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct fscache_cookie *cookie = fscache_cres_cookie(cres);
@@ -501,6 +496,36 @@ static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest *
return ret;
}
+/*
+ * Prepare a read operation, shortening it to a cached/uncached
+ * boundary as appropriate.
+ */
+static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest *subreq,
+ loff_t i_size)
+{
+ return cachefiles_do_prepare_read(subreq,
+ &subreq->rreq->cache_resources, i_size);
+}
+
+/*
+ * Prepare an on-demand read operation, shortening it to a cached/uncached
+ * boundary as appropriate.
+ */
+static enum netfs_io_source cachefiles_prepare_ondemand_read(struct netfs_cache_resources *cres,
+ loff_t start, size_t *_len, loff_t i_size)
+{
+ enum netfs_io_source source;
+ struct netfs_io_subrequest subreq = {
+ .start = start,
+ .len = *_len,
+ .flags = 1 << NETFS_SREQ_ONDEMAND,
+ };
+
+ source = cachefiles_do_prepare_read(&subreq, cres, i_size);
+ *_len = subreq.len;
+ return source;
+}
+
/*
* Prepare for a write to occur.
*/
@@ -621,6 +646,7 @@ static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
.write = cachefiles_write,
.prepare_read = cachefiles_prepare_read,
.prepare_write = cachefiles_prepare_write,
+ .prepare_ondemand_read = cachefiles_prepare_ondemand_read,
.query_occupancy = cachefiles_query_occupancy,
};
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index f2402ddeafbf..d82071c37133 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -267,6 +267,13 @@ struct netfs_cache_ops {
loff_t *_start, size_t *_len, loff_t i_size,
bool no_space_allocated_yet);
+ /* Prepare an on-demand read operation, shortening it to a cached/uncached
+ * boundary as appropriate.
+ */
+ enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
+ loff_t start, size_t *_len,
+ loff_t i_size);
+
/* Query the occupancy of the cache in a region, returning where the
* next chunk of data starts and how long it is.
*/
diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h
index d8d4d73fe7b6..655d5900b8ef 100644
--- a/include/trace/events/cachefiles.h
+++ b/include/trace/events/cachefiles.h
@@ -448,14 +448,14 @@ TRACE_EVENT(cachefiles_prep_read,
),
TP_fast_assign(
- __entry->rreq = sreq->rreq->debug_id;
+ __entry->rreq = sreq->rreq ? sreq->rreq->debug_id : 0;
__entry->index = sreq->debug_index;
__entry->flags = sreq->flags;
__entry->source = source;
__entry->why = why;
__entry->len = sreq->len;
__entry->start = sreq->start;
- __entry->netfs_inode = sreq->rreq->inode->i_ino;
+ __entry->netfs_inode = sreq->rreq ? sreq->rreq->inode->i_ino : 0;
__entry->cache_inode = cache_inode;
),
--
2.19.1.6.gb485710b
--
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