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authorAndrew Gallagher <agallagher@fb.com>2013-11-05 16:05:52 +0100
committerMiklos Szeredi <mszeredi@suse.cz>2014-01-22 19:36:59 +0100
commit7678ac50615d9c7a491d9861e020e4f5f71b594c (patch)
tree0625a52697800b032fd60b652833cf0ba04e43ae /fs/fuse
parent451418fc928b5ec1ee96a9afac807b6312811a2a (diff)
downloadlinux-7678ac50615d9c7a491d9861e020e4f5f71b594c.tar.bz2
fuse: support clients that don't implement 'open'
open/release operations require userspace transitions to keep track of the open count and to perform any FS-specific setup. However, for some purely read-only FSs which don't need to perform any setup at open/release time, we can avoid the performance overhead of calling into userspace for open/release calls. This patch adds the necessary support to the fuse kernel modules to prevent open/release operations from hitting in userspace. When the client returns ENOSYS, we avoid sending the subsequent release to userspace, and also remember this so that future opens also don't trigger a userspace operation. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Diffstat (limited to 'fs/fuse')
-rw-r--r--fs/fuse/file.c37
-rw-r--r--fs/fuse/fuse_i.h3
2 files changed, 30 insertions, 10 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index d53af8f15236..74f6ca500504 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -127,7 +127,15 @@ static void fuse_file_put(struct fuse_file *ff, bool sync)
if (atomic_dec_and_test(&ff->count)) {
struct fuse_req *req = ff->reserved_req;
- if (sync) {
+ if (ff->fc->no_open) {
+ /*
+ * Drop the release request when client does not
+ * implement 'open'
+ */
+ req->background = 0;
+ path_put(&req->misc.release.path);
+ fuse_put_request(ff->fc, req);
+ } else if (sync) {
req->background = 0;
fuse_request_send(ff->fc, req);
path_put(&req->misc.release.path);
@@ -144,27 +152,36 @@ static void fuse_file_put(struct fuse_file *ff, bool sync)
int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
bool isdir)
{
- struct fuse_open_out outarg;
struct fuse_file *ff;
- int err;
int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
ff = fuse_file_alloc(fc);
if (!ff)
return -ENOMEM;
- err = fuse_send_open(fc, nodeid, file, opcode, &outarg);
- if (err) {
- fuse_file_free(ff);
- return err;
+ ff->fh = 0;
+ ff->open_flags = FOPEN_KEEP_CACHE; /* Default for no-open */
+ if (!fc->no_open || isdir) {
+ struct fuse_open_out outarg;
+ int err;
+
+ err = fuse_send_open(fc, nodeid, file, opcode, &outarg);
+ if (!err) {
+ ff->fh = outarg.fh;
+ ff->open_flags = outarg.open_flags;
+
+ } else if (err != -ENOSYS || isdir) {
+ fuse_file_free(ff);
+ return err;
+ } else {
+ fc->no_open = 1;
+ }
}
if (isdir)
- outarg.open_flags &= ~FOPEN_DIRECT_IO;
+ ff->open_flags &= ~FOPEN_DIRECT_IO;
- ff->fh = outarg.fh;
ff->nodeid = nodeid;
- ff->open_flags = outarg.open_flags;
file->private_data = fuse_file_get(ff);
return 0;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index dc44b9e3a0c9..2da5db2c8bdb 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -485,6 +485,9 @@ struct fuse_conn {
* and hence races in setting them will not cause malfunction
*/
+ /** Is open/release not implemented by fs? */
+ unsigned no_open:1;
+
/** Is fsync not implemented by fs? */
unsigned no_fsync:1;