Implement lseek operation (#457)

diff --git a/ChangeLog.rst b/ChangeLog.rst
index 4d568e1df806401cbfd6a50c94757f557e0b1fa9..a37b63f481a48382f13b85d35530f1f470a3ba40 100644 (file)
--- a/ChangeLog.rst
+++ b/ChangeLog.rst
@@ -1,3 +1,9 @@
+Unreleased Changes
+==================
+
+* Added support for FUSE_LSEEK operation which can be used to report holes
+  in sparse files.
+
 libfuse 3.7.0 (2019-09-27)
 ==========================
 

diff --git a/example/passthrough.c b/example/passthrough.c
index 6de9fc1ba1012b447334eff23953786ff66611d8..012bd31c3c8dec9f32b3c38ed8f5d778aa38eb31 100644 (file)
--- a/example/passthrough.c
+++ b/example/passthrough.c
@@ -484,6 +484,28 @@ static ssize_t xmp_copy_file_range(const char *path_in,
 }
 #endif
 
+static off_t xmp_lseek(const char *path, off_t off, int whence, struct fuse_file_info *fi)
+{
+       int fd;
+       off_t res;
+
+       if (fi == NULL)
+               fd = open(path, O_RDONLY);
+       else
+               fd = fi->fh;
+
+       if (fd == -1)
+               return -errno;
+
+       res = lseek(fd, off, whence);
+       if (res == -1)
+               res = -errno;
+
+       if (fi == NULL)
+               close(fd);
+       return res;
+}
+
 static struct fuse_operations xmp_oper = {
        .init           = xmp_init,
        .getattr        = xmp_getattr,
@@ -522,6 +544,7 @@ static struct fuse_operations xmp_oper = {
 #ifdef HAVE_COPY_FILE_RANGE
        .copy_file_range = xmp_copy_file_range,
 #endif
+       .lseek          = xmp_lseek,
 };
 
 int main(int argc, char *argv[])

diff --git a/example/passthrough_fh.c b/example/passthrough_fh.c
index 3fc80f8f75dab77d01ff143dc26271036968881a..13eb41e3bdb1847a2cff7de03bfa505acea4eaaf 100644 (file)
--- a/example/passthrough_fh.c
+++ b/example/passthrough_fh.c
@@ -596,6 +596,18 @@ static ssize_t xmp_copy_file_range(const char *path_in,
 }
 #endif
 
+static off_t xmp_lseek(const char *path, off_t off, int whence, struct fuse_file_info *fi)
+{
+       off_t res;
+       (void) path;
+
+       res = lseek(fi->fh, off, whence);
+       if (res == -1)
+               return -errno;
+
+       return res;
+}
+
 static struct fuse_operations xmp_oper = {
        .init           = xmp_init,
        .getattr        = xmp_getattr,
@@ -643,6 +655,7 @@ static struct fuse_operations xmp_oper = {
 #ifdef HAVE_COPY_FILE_RANGE
        .copy_file_range = xmp_copy_file_range,
 #endif
+       .lseek          = xmp_lseek,
 };
 
 int main(int argc, char *argv[])

diff --git a/example/passthrough_ll.c b/example/passthrough_ll.c
index 0f1fda594324700afd2ca93018311d8af674078f..5372d02934a6458cf01ef8948efe463394ef86e4 100644 (file)
--- a/example/passthrough_ll.c
+++ b/example/passthrough_ll.c
@@ -1161,6 +1161,19 @@ static void lo_copy_file_range(fuse_req_t req, fuse_ino_t ino_in, off_t off_in,
 }
 #endif
 
+static void lo_lseek(fuse_req_t req, fuse_ino_t ino, off_t off, int whence,
+                    struct fuse_file_info *fi)
+{
+       off_t res;
+
+       (void)ino;
+       res = lseek(fi->fh, off, whence);
+       if (res != -1)
+               fuse_reply_lseek(req, res);
+       else
+               fuse_reply_err(req, errno);
+}
+
 static struct fuse_lowlevel_ops lo_oper = {
        .init           = lo_init,
        .lookup         = lo_lookup,
@@ -1198,6 +1211,7 @@ static struct fuse_lowlevel_ops lo_oper = {
 #ifdef HAVE_COPY_FILE_RANGE
        .copy_file_range = lo_copy_file_range,
 #endif
+       .lseek          = lo_lseek,
 };
 
 int main(int argc, char *argv[])

diff --git a/include/fuse.h b/include/fuse.h
index 2d2291c06fc52e5bc864bf754ab5a11e6631f2d9..883f6e59fb4333021a650ca78797a459fe3096ee 100644 (file)
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -776,6 +776,11 @@ struct fuse_operations {
                                    off_t offset_in, const char *path_out,
                                    struct fuse_file_info *fi_out,
                                    off_t offset_out, size_t size, int flags);
+
+       /**
+        * Find next data or hole after the specified offset
+        */
+       off_t (*lseek) (const char *, off_t off, int whence, struct fuse_file_info *);
 };
 
 /** Extra context that may be needed by some filesystems
@@ -1197,6 +1202,8 @@ ssize_t fuse_fs_copy_file_range(struct fuse_fs *fs, const char *path_in,
                                const char *path_out,
                                struct fuse_file_info *fi_out, off_t off_out,
                                size_t len, int flags);
+off_t fuse_fs_lseek(struct fuse_fs *fs, const char *path, off_t off, int whence,
+                   struct fuse_file_info *fi);
 void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn,
                struct fuse_config *cfg);
 void fuse_fs_destroy(struct fuse_fs *fs);

diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 207346081ec3fc618b5dd9fa025dabc3dae4e0e1..18c6363f07d8e87acd7353d0dba1686272c2e3de 100644 (file)
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1218,6 +1218,27 @@ struct fuse_lowlevel_ops {
                                 fuse_ino_t ino_out, off_t off_out,
                                 struct fuse_file_info *fi_out, size_t len,
                                 int flags);
+
+       /**
+        * Find next data or hole after the specified offset
+        *
+        * If this request is answered with an error code of ENOSYS, this is
+        * treated as a permanent failure, i.e. all future lseek() requests will
+        * fail with the same error code without being send to the filesystem
+        * process.
+        *
+        * Valid replies:
+        *   fuse_reply_lseek
+        *   fuse_reply_err
+        *
+        * @param req request handle
+        * @param ino the inode number
+        * @param off offset to start search from
+        * @param whence either SEEK_DATA or SEEK_HOLE
+        * @param fi file information
+        */
+       void (*lseek) (fuse_req_t req, fuse_ino_t ino, off_t off, int whence,
+                      struct fuse_file_info *fi);
 };
 
 /**
@@ -1569,6 +1590,18 @@ int fuse_reply_ioctl_iov(fuse_req_t req, int result, const struct iovec *iov,
  */
 int fuse_reply_poll(fuse_req_t req, unsigned revents);
 
+/**
+ * Reply with offset
+ *
+ * Possible requests:
+ *   lseek
+ *
+ * @param req request handle
+ * @param off offset of next data or hole
+ * @return zero for success, -errno for failure to send reply
+ */
+int fuse_reply_lseek(fuse_req_t req, off_t off);
+
 /* ----------------------------------------------------------- *
  * Notification                                                       *
  * ----------------------------------------------------------- */

diff --git a/lib/fuse.c b/lib/fuse.c
index 229e139d7b3b02580d4d3331cf3eca170867787c..b0f5b304ec95689ba473b0ae7615d676a61a5ffe 100755 (executable)
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2384,6 +2384,23 @@ ssize_t fuse_fs_copy_file_range(struct fuse_fs *fs, const char *path_in,
                return -ENOSYS;
 }
 
+off_t fuse_fs_lseek(struct fuse_fs *fs, const char *path, off_t off, int whence,
+                   struct fuse_file_info *fi)
+{
+       fuse_get_context()->private_data = fs->user_data;
+       if (fs->op.lseek) {
+               if (fs->debug) {
+                       char buf[10];
+                       fuse_log(FUSE_LOG_DEBUG, "lseek[%s] %llu %d\n",
+                               file_info_string(fi, buf, sizeof(buf)),
+                               (unsigned long long) off, whence);
+               }
+               return fs->op.lseek(path, off, whence, fi);
+       } else {
+               return -ENOSYS;
+       }
+}
+
 static int is_open(struct fuse *f, fuse_ino_t dir, const char *name)
 {
        struct node *node;
@@ -4354,6 +4371,31 @@ static void fuse_lib_copy_file_range(fuse_req_t req, fuse_ino_t nodeid_in,
        free_path(f, nodeid_out, path_out);
 }
 
+static void fuse_lib_lseek(fuse_req_t req, fuse_ino_t ino, off_t off, int whence,
+                          struct fuse_file_info *fi)
+{
+       struct fuse *f = req_fuse_prepare(req);
+       struct fuse_intr_data d;
+       char *path;
+       int err;
+       off_t res;
+
+       err = get_path(f, ino, &path);
+       if (err) {
+               reply_err(req, err);
+               return;
+       }
+
+       fuse_prepare_interrupt(f, req, &d);
+       res = fuse_fs_lseek(f->fs, path, off, whence, fi);
+       fuse_finish_interrupt(f, req, &d);
+       free_path(f, ino, path);
+       if (res >= 0)
+               fuse_reply_lseek(req, res);
+       else
+               reply_err(req, res);
+}
+
 static int clean_delay(struct fuse *f)
 {
        /*
@@ -4451,6 +4493,7 @@ static struct fuse_lowlevel_ops fuse_path_ops = {
        .poll = fuse_lib_poll,
        .fallocate = fuse_lib_fallocate,
        .copy_file_range = fuse_lib_copy_file_range,
+       .lseek = fuse_lib_lseek,
 };
 
 int fuse_notify_poll(struct fuse_pollhandle *ph)

diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index f7fbc8f5dbf46ae2abc53edf3213968e10914298..f2d7038e34dd15b0ed349e6b14f73518044562a3 100644 (file)
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -1065,6 +1065,16 @@ int fuse_reply_poll(fuse_req_t req, unsigned revents)
        return send_reply_ok(req, &arg, sizeof(arg));
 }
 
+int fuse_reply_lseek(fuse_req_t req, off_t off)
+{
+       struct fuse_lseek_out arg;
+
+       memset(&arg, 0, sizeof(arg));
+       arg.offset = off;
+
+       return send_reply_ok(req, &arg, sizeof(arg));
+}
+
 static void do_lookup(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 {
        char *name = (char *) inarg;
@@ -1867,6 +1877,20 @@ static void do_copy_file_range(fuse_req_t req, fuse_ino_t nodeid_in, const void
                fuse_reply_err(req, ENOSYS);
 }
 
+static void do_lseek(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
+{
+       struct fuse_lseek_in *arg = (struct fuse_lseek_in *) inarg;
+       struct fuse_file_info fi;
+
+       memset(&fi, 0, sizeof(fi));
+       fi.fh = arg->fh;
+
+       if (req->se->op.lseek)
+               req->se->op.lseek(req, nodeid, arg->offset, arg->whence, &fi);
+       else
+               fuse_reply_err(req, ENOSYS);
+}
+
 static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 {
        struct fuse_init_in *arg = (struct fuse_init_in *) inarg;
@@ -2471,6 +2495,7 @@ static struct {
        [FUSE_READDIRPLUS] = { do_readdirplus,  "READDIRPLUS"},
        [FUSE_RENAME2]     = { do_rename2,      "RENAME2"    },
        [FUSE_COPY_FILE_RANGE] = { do_copy_file_range, "COPY_FILE_RANGE" },
+       [FUSE_LSEEK]       = { do_lseek,       "LSEEK"       },
        [CUSE_INIT]        = { cuse_lowlevel_init, "CUSE_INIT"   },
 };
 

diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 11ef1f7ebb210d157412f960ae424f09675834b3..160f11dab229d50baea2b591e040374cad8f3f74 100644 (file)
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -127,6 +127,8 @@ FUSE_3.0 {
                fuse_cmdline_help;
                fuse_apply_conn_info_opts;
                fuse_parse_conn_info_opts;
+               fuse_fs_lseek;
+               fuse_reply_lseek;
 
        local:
                *;

diff --git a/lib/modules/iconv.c b/lib/modules/iconv.c
index 431d02ca6e77934d1ee9b67204aded34c3f9a616..eb5edd8ebac3ce602c456a6b1cc859f6a6f857c1 100644 (file)
--- a/lib/modules/iconv.c
+++ b/lib/modules/iconv.c
@@ -554,6 +554,19 @@ static int iconv_bmap(const char *path, size_t blocksize, uint64_t *idx)
        return err;
 }
 
+static off_t iconv_lseek(const char *path, off_t off, int whence,
+                        struct fuse_file_info *fi)
+{
+       struct iconv *ic = iconv_get();
+       char *newpath;
+       int res = iconv_convpath(ic, path, &newpath, 0);
+       if (!res) {
+               res = fuse_fs_lseek(ic->next, newpath, off, whence, fi);
+               free(newpath);
+       }
+       return res;
+}
+
 static void *iconv_init(struct fuse_conn_info *conn,
                        struct fuse_config *cfg)
 {
@@ -612,6 +625,7 @@ static const struct fuse_operations iconv_oper = {
        .lock           = iconv_lock,
        .flock          = iconv_flock,
        .bmap           = iconv_bmap,
+       .lseek          = iconv_lseek,
 };
 
 static const struct fuse_opt iconv_opts[] = {

diff --git a/lib/modules/subdir.c b/lib/modules/subdir.c
index 23f58f81169df3a2f2372c449821df4df66e1c80..616c0eea3202e4ed874566618dba1bcee6a1bb8c 100644 (file)
--- a/lib/modules/subdir.c
+++ b/lib/modules/subdir.c
@@ -540,6 +540,19 @@ static int subdir_bmap(const char *path, size_t blocksize, uint64_t *idx)
        return err;
 }
 
+static off_t subdir_lseek(const char *path, off_t off, int whence,
+                         struct fuse_file_info *fi)
+{
+       struct subdir *ic = subdir_get();
+       char *newpath;
+       int res = subdir_addpath(ic, path, &newpath);
+       if (!res) {
+               res = fuse_fs_lseek(ic->next, newpath, off, whence, fi);
+               free(newpath);
+       }
+       return res;
+}
+
 static void *subdir_init(struct fuse_conn_info *conn,
                         struct fuse_config *cfg)
 {
@@ -594,6 +607,7 @@ static const struct fuse_operations subdir_oper = {
        .lock           = subdir_lock,
        .flock          = subdir_flock,
        .bmap           = subdir_bmap,
+       .lseek          = subdir_lseek,
 };
 
 static const struct fuse_opt subdir_opts[] = {