Thanks, Gao Xiang. Reviewed-by: [email protected] <mailto:[email protected]>
Thanks, Chengyu > 2026年5月19日 12:31，Gao Xiang <[email protected]> 写道： > > From: Chengyu Zhu <[email protected]> > > Wire up the ublk userspace block device backend into mount.erofs, > providing an alternative to nbd for block device exposure. > > Signed-off-by: Chengyu Zhu <[email protected]> > Signed-off-by: Gao Xiang <[email protected]> > --- > mount/main.c | 266 ++++++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 244 insertions(+), 22 deletions(-) > > diff --git a/mount/main.c b/mount/main.c > index 90fbdc68f88d..7713ba41058c 100644 > --- a/mount/main.c > +++ b/mount/main.c > @@ -23,6 +23,7 @@ > #include "../lib/liberofs_fanotify.h" > #endif > #include "../lib/liberofs_s3.h" > +#include "../lib/liberofs_ublk.h" > > #ifdef HAVE_LINUX_LOOP_H > #include <linux/loop.h> > @@ -51,6 +52,7 @@ struct loop_info { > > #define EROFSMOUNT_RUNDIR "/var/run/erofs" > #define EROFSMOUNT_NBD_REC_FMT EROFSMOUNT_RUNDIR > "/mountnbd_nbd%d" > +#define EROFSMOUNT_UBLK_REC_FMT EROFSMOUNT_RUNDIR "/mountublk_ublkb%d" > > #ifdef EROFS_FANOTIFY_ENABLED > #define EROFSMOUNT_FANOTIFY_HELP ", fanotify" > @@ -58,12 +60,19 @@ struct loop_info { > #define EROFSMOUNT_FANOTIFY_HELP "" > #endif > > +#ifdef HAVE_LIBURING > +#define EROFSMOUNT_UBLK_HELP ", ublk" > +#else > +#define EROFSMOUNT_UBLK_HELP "" > +#endif > + > enum erofs_backend_drv { > EROFSAUTO, > EROFSLOCAL, > EROFSFUSE, > EROFSNBD, > EROFSFANOTIFY, > + EROFSUBLK, > }; > > enum erofsmount_mode { > @@ -117,10 +126,10 @@ static void usage(int argc, char **argv) > " -d <0-9> set output verbosity; 0=quiet, > 9=verbose (default=%i)\n" > " -o options comma-separated list of mount > options\n" > " -t type[.subtype] filesystem type (and optional > subtype)\n" > - " subtypes: fuse, local, nbd" > EROFSMOUNT_FANOTIFY_HELP "\n" > + " subtypes: fuse, local, nbd" > EROFSMOUNT_FANOTIFY_HELP EROFSMOUNT_UBLK_HELP "\n" > " -u unmount the filesystem\n" > " --disconnect abort an existing NBD device > forcibly\n" > - " --reattach reattach to an existing NBD > device\n" > + " --reattach reattach to an existing NBD or > ublk device\n" > #ifdef OCIEROFS_ENABLED > "\n" > "OCI-specific options (EXPERIMENTAL, with -o):\n" > @@ -465,6 +474,12 @@ static int erofsmount_parse_options(int argc, char > **argv) > #else > erofs_err("fanotify backend support is > not built-in"); > return -EINVAL; > +#endif > + } else if (!strcmp(dot + 1, "ublk")) { > +#ifdef HAVE_LIBURING > + mountcfg.backend = EROFSUBLK; > +#else > + erofs_err("ublk backend support is not > built-in"); > #endif > } else { > erofs_err("invalid filesystem subtype > `%s`", dot + 1); > @@ -1399,11 +1414,29 @@ out_fork: > return num; > } > > +static int erofsmount_ublk_handler(void *ctx, struct erofs_ublk_request *req) > +{ > + struct erofs_vfile *vf = ctx; > + ssize_t ret; > + > + if (req->op != EROFS_UBLK_OP_READ) > + return -EOPNOTSUPP; > + > + ret = erofs_io_pread(vf, req->buf, req->nr_sectors << 9, > + req->start_sector << 9); > + if (ret < 0) > + return (int)ret; > + > + req->result = ret; > + return 0; > +} > + > static int erofsmount_reattach(const char *target) > { > struct erofsmount_nbd_ctx ctx = { .vd = &ctx._vd }; > + int ublk_dev_id, nbdnum, err; > + char ublk_recp[64]; > char *identifier; > - int nbdnum, err; > struct stat st; > FILE *f; > > @@ -1411,7 +1444,48 @@ static int erofsmount_reattach(const char *target) > if (err < 0) > return -errno; > > - if (!S_ISBLK(st.st_mode) || major(st.st_rdev) != EROFS_NBD_MAJOR) > + if (!S_ISBLK(st.st_mode)) > + return -ENOTBLK; > + > + if (sscanf(target, "/dev/ublkb%d", &ublk_dev_id) == 1) { > + if (!erofs_ublk_is_recoverable(ublk_dev_id)) { > + erofs_err("ublk device %d is not recoverable", > + ublk_dev_id); > + return -ENODEV; > + } > + snprintf(ublk_recp, sizeof(ublk_recp), > + EROFSMOUNT_UBLK_REC_FMT, ublk_dev_id); > + f = fopen(ublk_recp, "r"); > + if (!f) { > + erofs_err("cannot open recovery file %s: %s", > + ublk_recp, strerror(errno)); > + return -errno; > + } > + err = erofsmount_recovery_open_source(&ctx, f); > + if (err) > + return err; > + if (fork() == 0) { > + if (erofs_ublk_init() < 0) > + exit(EXIT_FAILURE); > + err = erofs_ublk_recover_dev(ublk_dev_id, > + erofsmount_ublk_handler, > + &ctx.vd); > + if (err) { > + erofs_err("erofs_ublk_recover_dev: %s", > + strerror(-err)); > + exit(EXIT_FAILURE); > + } > + erofs_ublk_start(ublk_dev_id, -1); > + unlink(ublk_recp); > + erofs_ublk_destroy(ublk_dev_id); > + erofs_io_close(ctx.vd); > + exit(EXIT_SUCCESS); > + } > + erofs_io_close(ctx.vd); > + return 0; > + } > + > + if (major(st.st_rdev) != EROFS_NBD_MAJOR) > return -ENOTBLK; > > nbdnum = erofs_nbd_get_index_from_minor(minor(st.st_rdev)); > @@ -2034,6 +2108,130 @@ out: > } > #endif > > +static int erofsmount_ublk(struct erofsmount_source *source, > + const char *mountpoint, const char *fstype, > + int flags, const char *options) > +{ > + int pipefd[2]; > + char dev_path[64]; > + pid_t pid; > + int dev_id, err; > + char ready; > + > + err = erofs_ublk_init(); > + if (err) { > + erofs_err("ublk not supported"); > + return err; > + } > + > + if (pipe(pipefd) < 0) > + return -errno; > + > + pid = fork(); > + if (pid < 0) { > + close(pipefd[0]); > + close(pipefd[1]); > + return -errno; > + } > + > + if (pid == 0) { > + struct erofsmount_nbd_ctx ctx = { .vd = &ctx._vd }; > + struct erofs_ublk_dev_info info = {}; > + char ublk_recp[64], *recp; > + struct stat st; > + > + close(pipefd[0]); > + > + err = erofsmount_open_source(&ctx, source); > + if (err) > + exit(EXIT_FAILURE); > + > + info.nr_hw_queues = 1; > + info.queue_depth = 64; > + info.max_io_buf_bytes = 65536; > + info.dev_id = -1; > + info.blkbits = 12; > + info.flags = EROFS_UBLK_F_USER_RECOVERY; > + > + if (source->type == EROFSMOUNT_SOURCE_LOCAL && > + erofs_io_fstat(ctx.vd, &st) == 0) > + info.dev_size = st.st_size; > + else > + info.dev_size = INT64_MAX; > + > + dev_id = erofs_ublk_create_dev(&info, > + erofsmount_ublk_handler, ctx.vd); > + if (dev_id < 0) { > + erofs_err("erofs_ublk_create_dev failed: %s", > + strerror(-dev_id)); > + exit(EXIT_FAILURE); > + } > + > + snprintf(ublk_recp, sizeof(ublk_recp), > + EROFSMOUNT_UBLK_REC_FMT, dev_id); > + recp = erofsmount_write_recovery_info(source); > + if (IS_ERR(recp)) { > + erofs_err("write_recovery_info: %s", > + strerror(-(int)PTR_ERR(recp))); > + } else { > + if (rename(recp, ublk_recp)) > + erofs_err("rename recovery: %s", > + strerror(errno)); > + free(recp); > + } > + > + if (write(pipefd[1], &dev_id, > + sizeof(dev_id)) != sizeof(dev_id)) > + exit(EXIT_FAILURE); > + > + err = erofs_ublk_start(dev_id, pipefd[1]); > + if (err) > + erofs_err("erofs_ublk_start: %s", > + strerror(-err)); > + > + unlink(ublk_recp); > + erofs_ublk_destroy(dev_id); > + erofs_io_close(ctx.vd); > + exit(EXIT_SUCCESS); > + } > + > + close(pipefd[1]); > + if (read(pipefd[0], &dev_id, sizeof(dev_id)) != > + sizeof(dev_id)) { > + waitpid(pid, NULL, 0); > + close(pipefd[0]); > + return -EIO; > + } > + > + snprintf(dev_path, sizeof(dev_path), > + "/dev/ublkb%d", dev_id); > + > + if (read(pipefd[0], &ready, 1) != 1) { > + waitpid(pid, NULL, 0); > + close(pipefd[0]); > + return -EIO; > + } > + close(pipefd[0]); > + > + err = mount(dev_path, mountpoint, fstype, flags, options); > + if (err < 0) { > + err = -errno; > + kill(pid, SIGTERM); > + waitpid(pid, NULL, 0); > + return err; > + } > + return 0; > +} > + > +static int ublk_dev_id_from_path(const char *path) > +{ > + int dev_id; > + > + if (sscanf(path, "/dev/ublkb%d", &dev_id) == 1) > + return dev_id; > + return -1; > +} > + > int erofsmount_umount(char *target) > { > char *device = NULL, *mountpoint = NULL; > @@ -2071,7 +2269,7 @@ int erofsmount_umount(char *target) > > for (s = NULL; (getline(&s, &n, mounts)) > 0;) { > bool hit = false; > - char *f1, *f2, *end; > + char *f1, *f2 = NULL, *end; > > f1 = s; > end = strchr(f1, ' '); > @@ -2088,31 +2286,48 @@ int erofsmount_umount(char *target) > hit = true; > } > if (hit) { > - if (isblk) { > - err = -EBUSY; > - free(s); > - fclose(mounts); > - goto err_out; > - } > free(device); > device = strdup(f1); > - if (!mountpoint) > - mountpoint = strdup(f2); > + free(mountpoint); > + mountpoint = f2 ? strdup(f2) : NULL; > } > } > free(s); > fclose(mounts); > + > + if (isblk && !device) { > + if (S_ISBLK(st.st_mode) && major(st.st_rdev) == > EROFS_NBD_MAJOR) { > + nbdnum = > erofs_nbd_get_index_from_minor(minor(st.st_rdev)); > + err = erofs_nbd_nl_disconnect(nbdnum); > + if (err != -EOPNOTSUPP) > + goto err_out; > + } > + err = ublk_dev_id_from_path(target); > + if (err >= 0) { > + err = erofs_ublk_del_dev_by_id(err); > + goto err_out; > + } > + err = -ENOENT; > + goto err_out; > + } > + > if (!isblk && !device) { > err = -ENOENT; > goto err_out; > } > > - if (isblk && !mountpoint && > - S_ISBLK(st.st_mode) && major(st.st_rdev) == EROFS_NBD_MAJOR) { > - nbdnum = erofs_nbd_get_index_from_minor(minor(st.st_rdev)); > - err = erofs_nbd_nl_disconnect(nbdnum); > - if (err != -EOPNOTSUPP) > - return err; > + err = ublk_dev_id_from_path(device); > + if (err >= 0) { > + if (mountpoint) { > + int ret = umount(mountpoint); > + > + if (ret) { > + err = -errno; > + goto err_out; > + } > + } > + err = erofs_ublk_del_dev_by_id(err); > + goto err_out; > } > > /* Avoid TOCTOU issue with NBD_CFLAG_DISCONNECT_ON_CLOSE */ > @@ -2224,13 +2439,20 @@ int main(int argc, char *argv[]) > goto exit; > } > > - if (mountcfg.backend == EROFSNBD) { > + if (mountcfg.backend == EROFSNBD || mountcfg.backend == EROFSUBLK) { > if (mountsrc.type == EROFSMOUNT_SOURCE_OCI) > mountsrc.ocicfg.image_ref = mountcfg.device; > else > mountsrc.device_path = mountcfg.device; > - err = erofsmount_nbd(&mountsrc, mountcfg.target, > - mountcfg.fstype, mountcfg.flags, > mountcfg.options); > + > + if (mountcfg.backend == EROFSNBD) > + err = erofsmount_nbd(&mountsrc, mountcfg.target, > + mountcfg.fstype, mountcfg.flags, > + mountcfg.options); > + else > + err = erofsmount_ublk(&mountsrc, mountcfg.target, > + mountcfg.fstype, mountcfg.flags, > + mountcfg.options); > goto exit; > } > > -- > 2.43.5 >
