[PATCH v9 06/21] cachefiles: enable on-demand read mode

[Jeffle Xu]

Enable on-demand read mode by adding an optional parameter to the "bind"
command.

On-demand mode will be turned on when this parameter is "ondemand", i.e.
"bind ondemand". Otherwise cachefiles will work in the original mode.

Signed-off-by: Jeffle Xu <jefflexu at linux.alibaba.com>
---
 fs/cachefiles/daemon.c | 13 ++++++++-----
 fs/cachefiles/io.c     | 11 -----------
 2 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 2e946e4eb65a..c8bde21ace6a 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -758,11 +758,6 @@ static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
 	    cache->brun_percent  >= 100)
 		return -ERANGE;
 
-	if (*args) {
-		pr_err("'bind' command doesn't take an argument\n");
-		return -EINVAL;
-	}
-
 	if (!cache->rootdirname) {
 		pr_err("No cache directory specified\n");
 		return -EINVAL;
@@ -774,6 +769,14 @@ static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
 		return -EBUSY;
 	}
 
+	if (IS_ENABLED(CONFIG_CACHEFILES_ONDEMAND) &&
+	    !strcmp(args, "ondemand")) {
+		set_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags);
+	} else if (*args) {
+		pr_err("'bind' command doesn't take an argument\n");
+		return -EINVAL;
+	}
+
 	/* Make sure we have copies of the tag string */
 	if (!cache->tag) {
 		/*
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index ccf77a969653..000a28f46e59 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -95,7 +95,6 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
 	       file, file_inode(file)->i_ino, start_pos, len,
 	       i_size_read(file_inode(file)));
 
-retry:
 	/* If the caller asked us to seek for data before doing the read, then
 	 * we should do that now.  If we find a gap, we fill it with zeros.
 	 */
@@ -120,16 +119,6 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
 			if (read_hole == NETFS_READ_HOLE_FAIL)
 				goto presubmission_error;
 
-			if (read_hole == NETFS_READ_HOLE_ONDEMAND) {
-				ret = cachefiles_ondemand_read(object, off, len);
-				if (ret)
-					goto presubmission_error;
-
-				/* fail the read if no progress achieved */
-				read_hole = NETFS_READ_HOLE_FAIL;
-				goto retry;
-			}
-
 			iov_iter_zero(len, iter);
 			skipped = len;
 			ret = 0;
-- 
2.27.0