need fsinfo from btrfs-control that is when mount path is
not known.
current method of going through each mount points isn't
efficient, and multiple subvol of a fsid could be mounted
means extra logic to handle that. Further this will help
to revamp check_mounted() (planned)
check_mounted is heavily used in the btrfs-progs, it
does full scan of all the disks in the system to confirm
if a multi-disk btrfs is mounted it doesn't scalable well
with few hundreds luns, check_mounted for sure needs a
revamp. using this it can be done easily. which is planned.
Signed-off-by: Anand Jain <anand.j...@oracle.com>
v4: bug fix and accepts Stefan suggested
v3: accepts Josef suggested
v2: commit reword
---
ioctl.h | 19 ++++++++++++++++
utils.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
utils.h | 1 +
3 files changed, 95 insertions(+), 0 deletions(-)
diff --git a/ioctl.h b/ioctl.h
index d21413f..29575d8 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -506,6 +506,23 @@ static inline char *btrfs_err_str(enum btrfs_err_code
err_code)
}
}
+/* fs flags */
+#define BTRFS_FS_MOUNTED (1LLU << 0)
+
+struct btrfs_ioctl_fslist {
+ __u64 self_sz; /* in/out */
+ __u8 fsid[BTRFS_FSID_SIZE]; /* out */
+ __u64 num_devices;
+ __u64 missing_devices;
+ __u64 total_devices;
+ __u64 flags;
+};
+
+struct btrfs_ioctl_fslist_args {
+ __u64 self_sz; /* in/out */
+ __u64 count; /* out */
+};
+
#define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
struct btrfs_ioctl_vol_args)
#define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
@@ -604,6 +621,8 @@ struct btrfs_ioctl_clone_range_args {
struct btrfs_ioctl_dev_replace_args)
#define BTRFS_IOC_DEDUP_CTL _IOWR(BTRFS_IOCTL_MAGIC, 55, \
struct btrfs_ioctl_dedup_args)
+#define BTRFS_IOC_GET_FSLIST _IOWR(BTRFS_IOCTL_MAGIC, 56, \
+ struct btrfs_ioctl_fslist_args)
#ifdef __cplusplus
}
#endif
diff --git a/utils.c b/utils.c
index 60d2c3a..9983db2 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)
@@ -2087,3 +2088,77 @@ int lookup_ino_rootid(int fd, u64 *rootid)
return 0;
}
+
+/* scans for fsid(s) in the kernel using the btrfs-control
+ * interface.
+ */
+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;
+ u64 sz;
+ int count;
+
+ fd = open("/dev/btrfs-control", O_RDWR);
+ e = errno;
+ if (fd < 0) {
+ perror("failed to open /dev/btrfs-control");
+ return -e;
+ }
+
+ /* space to hold 512 fsids, doesn't matter if small
+ * it would fail and return count so then we try again
+ */
+ count = 512;
+again:
+ sz = sizeof(*fsargs) + sizeof(*fslist) * count;
+
+ fsargs_saved = fsargs = malloc(sz);
+ if (!fsargs) {
+ close(fd);
+ return -ENOMEM;
+ }
+
+ memset(fsargs, 0, sz);
+ fsargs->count = count;
+
+ ret = ioctl(fd, BTRFS_IOC_GET_FSLIST, fsargs);
+ e = errno;
+ if (ret == 1) {
+ /* out of size so reallocate */
+ count = fsargs->count;
+ free(fsargs);
+ goto again;
+ } else if (ret < 0) {
+ printf("ERROR: scan_fsid ioctl failed - %s\n",
+ strerror(e));
+ ret = -e;
+ goto out;
+ }
+
+ /* ioctl returns fsid count in count parameter*/
+
+ *out_count = fsargs->count;
+ if (*out_count == 0) {
+ *out_fslist = NULL;
+ ret = 0;
+ goto out;
+ }
+
+ fslist = (struct btrfs_ioctl_fslist *) (++fsargs);
+
+ sz = sizeof(*fslist) * *out_count;
+ *out_fslist = malloc(sz);
+ if (*out_fslist == NULL) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ memcpy(*out_fslist, fslist, sz);
+ ret = 0;
+out:
+ free(fsargs_saved);
+ close(fd);
+ return ret;
+}
diff --git a/utils.h b/utils.h
index 6f4b10c..a14a887 100644
--- a/utils.h
+++ b/utils.h
@@ -94,5 +94,6 @@ 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, u64 *out_count);
#endif
--
1.7.1
--
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