fuse: add support for SEEK_HOLE and SEEK_DATA through lseek()

The Linux FUSE kernel module has gained support for passing SEEK_HOLE
and SEEK_DATA on through lseek(). This can greatly improve performance
when working with sparse files.

Linux FUSE introduced support for lseek() with version 4.5. The commit
in mainline Linux is 0b5da8db145bfd44266ac964a2636a0cf8d7c286.

URL: http://thread.gmane.org/gmane.comp.file-systems.fuse.devel/14752
Change-Id: I12496d788e59461a3023ddd30e0ea3179007f77e
BUG: 1220173
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/11474
Smoke: Gluster Build System <jenkins@build.gluster.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

2 files changed, 67 insertions, 1 deletions

diff --git a/xlators/mount/fuse/src/fuse-bridge.c b/xlators/mount/fuse/src/fuse-bridge.c
index 724a70b8149..ff42ec11273 100644
--- a/xlators/mount/fuse/src/fuse-bridge.c
+++ b/xlators/mount/fuse/src/fuse-bridge.c
@@ -2393,6 +2393,66 @@ fuse_write (xlator_t *this, fuse_in_header_t *finh, void *msg)
         return;
 }
 
+#if FUSE_KERNEL_MINOR_VERSION >= 24 && HAVE_SEEK_HOLE
+static int
+fuse_lseek_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
+                int32_t op_ret, int32_t op_errno, off_t offset, dict_t *xdata)
+{
+        fuse_state_t           *state = frame->root->state;
+        fuse_in_header_t       *finh  = state->finh;
+        struct fuse_lseek_out   flo   = {0, };
+
+        fuse_log_eh_fop (this, state, frame, op_ret, op_errno);
+
+        if (op_ret >= 0) {
+                flo.offset = offset;
+                send_fuse_obj (this, finh, &flo);
+        } else {
+                send_fuse_err (this, finh, op_errno);
+        }
+
+        free_fuse_state (state);
+        STACK_DESTROY (frame->root);
+
+        return 0;
+}
+
+static void
+fuse_lseek_resume (fuse_state_t *state)
+{
+        FUSE_FOP (state, fuse_lseek_cbk, GF_FOP_SEEK, seek, state->fd,
+                  state->off, state->whence, state->xdata);
+}
+
+static void
+fuse_lseek (xlator_t *this, fuse_in_header_t *finh, void *msg)
+{
+        struct fuse_lseek_in *ffi   = msg;
+        fuse_state_t         *state = NULL;
+
+        GET_STATE (this, finh, state);
+        state->fd = FH_TO_FD (ffi->fh);
+        state->off = ffi->offset;
+
+        switch (ffi->whence) {
+        case SEEK_DATA:
+                state->whence = GF_SEEK_DATA;
+                break;
+        case SEEK_HOLE:
+                state->whence = GF_SEEK_HOLE;
+                break;
+        default:
+                /* fuse should handle other whence internally */
+                send_fuse_err (this, finh, EINVAL);
+                free_fuse_state (state);
+                return;
+        }
+
+        fuse_resolve_fd_init (state, &state->resolve, state->fd);
+        fuse_resolve_and_resume (state, fuse_lseek_resume);
+}
+#endif /* FUSE_KERNEL_MINOR_VERSION >= 24 && HAVE_SEEK_HOLE */
+
 void
 fuse_flush_resume (fuse_state_t *state)
 {
@@ -5327,6 +5387,10 @@ static fuse_handler_t *fuse_std_ops[FUSE_OP_HIGH] = {
 #if FUSE_KERNEL_MINOR_VERSION >= 21
 	[FUSE_READDIRPLUS] = fuse_readdirp,
 #endif
+
+#if FUSE_KERNEL_MINOR_VERSION >= 24 && HAVE_SEEK_HOLE
+        [FUSE_LSEEK]        = fuse_lseek,
+#endif
 };
 
 
diff --git a/xlators/mount/fuse/src/fuse-bridge.h b/xlators/mount/fuse/src/fuse-bridge.h
index d337ea08539..1da04c57f8f 100644
--- a/xlators/mount/fuse/src/fuse-bridge.h
+++ b/xlators/mount/fuse/src/fuse-bridge.h
@@ -41,7 +41,7 @@
 #include "gidcache.h"
 
 #if defined(GF_LINUX_HOST_OS) || defined(__FreeBSD__) || defined(__NetBSD__)
-#define FUSE_OP_HIGH (FUSE_READDIRPLUS + 1)
+#define FUSE_OP_HIGH (FUSE_LSEEK + 1)
 #endif
 #ifdef GF_DARWIN_HOST_OS
 #define FUSE_OP_HIGH (FUSE_DESTROY + 1)
@@ -380,6 +380,8 @@ typedef struct {
         uuid_t         gfid;
         uint32_t       io_flags;
         int32_t        fd_no;
+
+        gf_seek_what_t whence;
 } fuse_state_t;
 
 typedef struct {