diff mbox series

[RFC,46/61] cachefiles: Shape write requests

Message ID 158861246621.340223.9118210695394840507.stgit@warthog.procyon.org.uk
State New
Headers show
Series [RFC,01/61] afs: Make afs_zap_data() static | expand

Commit Message

David Howells May 4, 2020, 5:14 p.m. UTC
In cachefiles_shape_extent(), shape a write request to always write to the
cache.  The assumption is made that the caller has read the entire cache
granule beforehand if necessary.

Possibly this should be amended so that writes will only take place to
granules that are marked present and granules that lie beyond the EOF.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/cachefiles/content-map.c |   22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/fs/cachefiles/content-map.c b/fs/cachefiles/content-map.c
index 13632c097248..2c45092465b6 100644
--- a/fs/cachefiles/content-map.c
+++ b/fs/cachefiles/content-map.c
@@ -71,7 +71,8 @@  static unsigned int cachefiles_shape_single(struct fscache_object *obj,
 
 	extent->dio_block_size = CACHEFILES_DIO_BLOCK_SIZE;
 
-	if (object->content_info == CACHEFILES_CONTENT_SINGLE) {
+	if (!for_write &&
+	    object->content_info == CACHEFILES_CONTENT_SINGLE) {
 		ret = FSCACHE_READ_FROM_CACHE;
 	} else {
 		eof = (i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -128,13 +129,20 @@  unsigned int cachefiles_shape_extent(struct fscache_object *obj,
 
 	granule = start / CACHEFILES_GRAN_PAGES;
 
-	/* If the content map didn't get expanded for some reason - simply
-	 * ignore this granule.
-	 */
-	if (granule / 8 >= object->content_map_size)
-		return 0;
+	if (granule / 8 >= object->content_map_size) {
+		cachefiles_expand_content_map(object, i_size);
+		if (granule / 8 >= object->content_map_size)
+			return 0;
+	}
 
-	if (cachefiles_granule_is_present(object, granule)) {
+	if (for_write) {
+		/* Assume that the preparation to write involved preloading any
+		 * bits of the cache that weren't to be written and filling any
+		 * gaps that didn't end up being written.
+		 */
+		bend = end;
+		ret = FSCACHE_WRITE_TO_CACHE;
+	} else if (cachefiles_granule_is_present(object, granule)) {
 		/* The start of the requested extent is present in the cache -
 		 * restrict the returned extent to the maximum length of what's
 		 * available.