as of now with out this patch user would see
fsinfo per btrfs mount path but which mean multiple
entry if more than one subvol is mounted of the same
fsid. so this patch will handle that nicely.

v2: accepts Zach suggested

Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
 cmds-filesystem.c |   90 +++++++++++++++++++++++++++++++++--------------------
 utils.c           |   88 ++++++++++++++++++++++++++++++++++++++++++---------
 utils.h           |    3 +-
 3 files changed, 130 insertions(+), 51 deletions(-)

diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index d2cad81..f8e8475 100644
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -317,6 +317,29 @@ static int print_one_fs(struct btrfs_ioctl_fs_info_args 
*fs_info,
        return 0;
 }
 
+static void handle_print(char *mnt, char *label)
+{
+       int fd;
+       struct btrfs_ioctl_fs_info_args fs_info_arg;
+       struct btrfs_ioctl_dev_info_args *dev_info_arg = NULL;
+       struct btrfs_ioctl_space_args *space_info_arg;
+
+       if (get_fs_info(mnt, &fs_info_arg, &dev_info_arg)) {
+               fprintf(stdout, "ERROR: get_fs_info failed\n");
+               return;
+       }
+
+       fd = open(mnt, O_RDONLY);
+       if (fd > 0 && !get_df(fd, &space_info_arg)) {
+               print_one_fs(&fs_info_arg, dev_info_arg,
+                               space_info_arg, label, mnt);
+               kfree(space_info_arg);
+       }
+       if (fd > 0)
+               close(fd);
+       kfree(dev_info_arg);
+}
+
 /* This function checks if the given input parameter is
  * an uuid or a path
  * return -1: some error in the given input
@@ -350,47 +373,39 @@ static int check_arg_type(char *input)
 
 static int btrfs_scan_kernel(void *search)
 {
-       int ret = 0, fd;
-       FILE *f;
-       struct mntent *mnt;
-       struct btrfs_ioctl_fs_info_args fs_info_arg;
-       struct btrfs_ioctl_dev_info_args *dev_info_arg = NULL;
-       struct btrfs_ioctl_space_args *space_info_arg;
+       int ret = 0;
        char label[BTRFS_LABEL_SIZE];
-
-       f = setmntent("/proc/self/mounts", "r");
-       if (f == NULL)
-               return 1;
-
-       memset(label, 0, sizeof(label));
-       while ((mnt = getmntent(f)) != NULL) {
-               if (strcmp(mnt->mnt_type, "btrfs"))
+       char mnt[BTRFS_PATH_NAME_MAX + 1];
+       struct btrfs_ioctl_fslist *fslist;
+       struct btrfs_ioctl_fslist *fslist_saved;
+       u64 cnt_fs;
+       int cnt_mnt;
+       __u8 *fsid;
+       __u64 flags;
+
+       ret = get_fslist(&fslist, &cnt_fs);
+       if (ret)
+               return ret;
+       fslist_saved = fslist;
+       while (cnt_fs--) {
+               fsid = fslist->fsid;
+               flags = fslist->flags;
+               fslist++;
+               if (!(flags & BTRFS_FS_MOUNTED))
                        continue;
-               ret = get_fs_info(mnt->mnt_dir, &fs_info_arg,
-                               &dev_info_arg);
+               memset(mnt, 0, BTRFS_PATH_NAME_MAX + 1);
+               memset(label, 0, sizeof(label));
+               ret = fsid_to_mntpt(fsid, mnt, &cnt_mnt);
                if (ret)
                        return ret;
-
-               if (get_label_mounted(mnt->mnt_dir, label)) {
-                       kfree(dev_info_arg);
+               if (get_label_mounted(mnt, label))
                        return 1;
-               }
-               if (search && !match_search_item_kernel(fs_info_arg.fsid,
-                                       mnt->mnt_dir, label, search)) {
-                       kfree(dev_info_arg);
+
+               if (search && !match_search_item_kernel(fsid,
+                                       mnt, label, search))
                        continue;
-               }
 
-               fd = open(mnt->mnt_dir, O_RDONLY);
-               if (fd > 0 && !get_df(fd, &space_info_arg)) {
-                       print_one_fs(&fs_info_arg, dev_info_arg,
-                                       space_info_arg, label, mnt->mnt_dir);
-                       kfree(space_info_arg);
-                       memset(label, 0, sizeof(label));
-               }
-               if (fd > 0)
-                       close(fd);
-               kfree(dev_info_arg);
+               handle_print(mnt, label);
                if (search)
                        return 0;
        }
@@ -469,6 +484,13 @@ static int cmd_show(int argc, char **argv)
                                        goto devs_only;
                        }
                }
+               if (type == BTRFS_ARG_MNTPOINT) {
+                       char label[BTRFS_LABEL_SIZE];
+                       if (get_label_mounted(search, label))
+                               return 1;
+                       handle_print(search, label);
+                       return 0;
+               }
        }
 
        if (where == BTRFS_SCAN_DEV)
diff --git a/utils.c b/utils.c
index 1798a7c..d466ffa 100644
--- a/utils.c
+++ b/utils.c
@@ -47,6 +47,7 @@
 #include "utils.h"
 #include "volumes.h"
 #include "ioctl.h"
+#include "btrfs-list.h"
 
 #ifndef BLKDISCARD
 #define BLKDISCARD     _IO(0x12,119)
@@ -2091,12 +2092,12 @@ int lookup_ino_rootid(int fd, u64 *rootid)
 /* scans for fsid(s) in the kernel using the btrfs-control
  * interface.
  */
-int get_fslist(struct btrfs_ioctl_fslist **out_fslist, int *out_count)
+int get_fslist(struct btrfs_ioctl_fslist **out_fslist, u64 *out_count)
 {
        int ret, fd, e;
        struct btrfs_ioctl_fslist_args *fsargs;
+       struct btrfs_ioctl_fslist_args *fsargs_saved = NULL;
        struct btrfs_ioctl_fslist *fslist;
-       struct btrfs_ioctl_fslist *fslist_tmp;
        u64 sz;
        int count;
 
@@ -2139,31 +2140,86 @@ again:
 
        /* ioctl returns fsid count in count parameter*/
 
-       *out_count = count = fsargs->count;
-       if (count == 0) {
+       *out_count = fsargs->count;
+       if (*out_count == 0) {
                *out_fslist = NULL;
                ret = 0;
                goto out;
        }
 
-       fslist = (struct btrfs_ioctl_fslist *) (fsargs +
-                                               sizeof(*fsargs));
+       fsargs_saved = fsargs;
+       fslist = (struct btrfs_ioctl_fslist *) (++fsargs);
 
-       fslist_tmp = *out_fslist = (struct btrfs_ioctl_fslist *)
-                               malloc(sizeof(*fslist) * count);
-       if (!fslist_tmp) {
+       sz = sizeof(*fslist) * *out_count;
+       *out_fslist = (struct btrfs_ioctl_fslist *) malloc(sz);
+       if (*out_fslist == NULL) {
                ret = -ENOMEM;
                goto out;
        }
-
-       while (count--) {
-               memcpy(fslist_tmp, fslist, sizeof(*fslist));
-               fslist_tmp = fslist_tmp + sizeof(*fslist_tmp);
-               fslist = fslist + sizeof(*fslist);
-       }
+       memcpy(*out_fslist, fslist, sz);
        ret = 0;
 out:
-       free(fsargs);
+       free(fsargs_saved);
        close(fd);
        return 0;
 }
+
+/* This finds the mount point for a given fsid,
+ *  subvols of the same fs/fsid can be mounted
+ *  so here this picks and lowest subvol id
+ *  and returns the mount point
+*/
+int fsid_to_mntpt(__u8 *fsid, char *mntpt, int *mnt_cnt)
+{
+       int fd = -1, ret = 0;
+       DIR *dirstream = NULL;
+       FILE *f;
+       struct btrfs_ioctl_fs_info_args fi_args;
+       u64 svid, saved_svid = (u64)-1;
+       struct mntent *mnt;
+       int mcnt = 0;
+
+       *mnt_cnt = 0;
+       f = setmntent("/proc/self/mounts", "r");
+       if (f == NULL)
+               return 1;
+
+       while ((mnt = getmntent(f)) != NULL) {
+               if (strcmp(mnt->mnt_type, "btrfs"))
+                       continue;
+               fd = open_file_or_dir(mnt->mnt_dir, &dirstream);
+               if (fd < 0) {
+                       ret = -errno;
+                       return ret;
+               }
+               ret = ioctl(fd, BTRFS_IOC_FS_INFO, &fi_args);
+               if (ret < 0) {
+                       ret = -errno;
+                       close_file_or_dir(fd, dirstream);
+                       break;
+               }
+               if (uuid_compare(fsid, fi_args.fsid)) {
+                       close_file_or_dir(fd, dirstream);
+                       continue;
+               }
+
+               /* found */
+               mcnt++;
+               ret = btrfs_list_get_path_rootid(fd, &svid);
+               if (ret) {
+                       /* error so just copy and return*/
+                       strcpy(mntpt, mnt->mnt_dir);
+                       close_file_or_dir(fd, dirstream);
+                       break;
+               }
+               if (svid < saved_svid) {
+                       strcpy(mntpt, mnt->mnt_dir);
+                       saved_svid = svid;
+               }
+       }
+       endmntent(f);
+       if (mcnt)
+               *mnt_cnt = mcnt;
+
+       return ret;
+}
diff --git a/utils.h b/utils.h
index e20ad74..8c64575 100644
--- a/utils.h
+++ b/utils.h
@@ -94,6 +94,7 @@ int ask_user(char *question);
 int lookup_ino_rootid(int fd, u64 *rootid);
 int btrfs_scan_lblkid(int update_kernel);
 int get_btrfs_mount(const char *dev, char *mp, size_t mp_size);
-int get_fslist(struct btrfs_ioctl_fslist **out_fslist, int *out_count);
+int get_fslist(struct btrfs_ioctl_fslist **out_fslist, u64 *out_count);
+int fsid_to_mntpt(__u8 *fsid, char *mnt, int *mnt_cnt);
 
 #endif
-- 
1.7.1

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