[fuse-devel] [PATCH] Add legacy_cache mount option.

[Brian F. <bf...@re...>]

Several caching logic changes have been made on the kernel side
to better support network-based fuse filesystems. These include
kernel side mtime checking and read path cache revalidation. The
original caching logic is preserved through the FUSE_LEGACY_CACHE
init flag. Export this to the user via the 'legacy_cache' mount
option.
---
 include/fuse_common.h |    1 +
 include/fuse_kernel.h |    1 +
 lib/fuse_i.h          |    1 +
 lib/fuse_lowlevel.c   |    8 ++++++++
 4 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/include/fuse_common.h b/include/fuse_common.h
index a4d980d..1262911 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -112,6 +112,7 @@ struct fuse_file_info {
 #define FUSE_CAP_SPLICE_READ	(1 << 9)
 #define FUSE_CAP_FLOCK_LOCKS	(1 << 10)
 #define FUSE_CAP_IOCTL_DIR	(1 << 11)
+#define FUSE_CAP_LEGACY_CACHE	(1 << 12)
 
 /**
  * Ioctl flags
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index c632b58..715b3b5 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -207,6 +207,7 @@ struct fuse_file_lock {
 #define FUSE_BIG_WRITES		(1 << 5)
 #define FUSE_DONT_MASK		(1 << 6)
 #define FUSE_FLOCK_LOCKS	(1 << 10)
+#define FUSE_LEGACY_CACHE	(1 << 12)
 
 /**
  * CUSE INIT request/reply flags
diff --git a/lib/fuse_i.h b/lib/fuse_i.h
index 78f1467..05a8d1f 100644
--- a/lib/fuse_i.h
+++ b/lib/fuse_i.h
@@ -71,6 +71,7 @@ struct fuse_ll {
 	int no_splice_write;
 	int no_splice_move;
 	int no_splice_read;
+	int legacy_cache;
 	struct fuse_lowlevel_ops op;
 	int got_init;
 	struct cuse_data *cuse_data;
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index a259f37..80b3913 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -1788,6 +1788,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 			f->conn.capable |= FUSE_CAP_DONT_MASK;
 		if (arg->flags & FUSE_FLOCK_LOCKS)
 			f->conn.capable |= FUSE_CAP_FLOCK_LOCKS;
+		if (arg->flags & FUSE_LEGACY_CACHE)
+			f->conn.capable |= FUSE_CAP_LEGACY_CACHE;
 	} else {
 		f->conn.async_read = 0;
 		f->conn.max_readahead = 0;
@@ -1818,6 +1820,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		f->conn.want |= FUSE_CAP_FLOCK_LOCKS;
 	if (f->big_writes)
 		f->conn.want |= FUSE_CAP_BIG_WRITES;
+	if (f->legacy_cache)
+		f->conn.want |= FUSE_CAP_LEGACY_CACHE;
 
 	if (bufsize < FUSE_MIN_READ_BUFFER) {
 		fprintf(stderr, "fuse: warning: buffer size too small: %zu\n",
@@ -1854,6 +1858,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		outarg.flags |= FUSE_DONT_MASK;
 	if (f->conn.want & FUSE_CAP_FLOCK_LOCKS)
 		outarg.flags |= FUSE_FLOCK_LOCKS;
+	if (f->conn.want & FUSE_CAP_LEGACY_CACHE)
+		outarg.flags |= FUSE_LEGACY_CACHE;
 	outarg.max_readahead = f->conn.max_readahead;
 	outarg.max_write = f->conn.max_write;
 	if (f->conn.proto_minor >= 13) {
@@ -2490,6 +2496,7 @@ static const struct fuse_opt fuse_ll_opts[] = {
 	{ "no_splice_move", offsetof(struct fuse_ll, no_splice_move), 1},
 	{ "splice_read", offsetof(struct fuse_ll, splice_read), 1},
 	{ "no_splice_read", offsetof(struct fuse_ll, no_splice_read), 1},
+	{ "legacy_cache", offsetof(struct fuse_ll, legacy_cache), 1},
 	FUSE_OPT_KEY("max_read=", FUSE_OPT_KEY_DISCARD),
 	FUSE_OPT_KEY("-h", KEY_HELP),
 	FUSE_OPT_KEY("--help", KEY_HELP),
@@ -2521,6 +2528,7 @@ static void fuse_ll_help(void)
 "    -o [no_]splice_write   use splice to write to the fuse device\n"
 "    -o [no_]splice_move    move data while splicing to the fuse device\n"
 "    -o [no_]splice_read    use splice to read from the fuse device\n"
+"    -o legacy_cache        use legacy cache invalidation logic\n"
 );
 }
 
-- 
1.7.7.6