btrfs-progs: Introduce device delete by devid

This patch introduces new option <devid> for the command

  btrfs device delete <device_path|devid>[..]  <mnt>

In a user reported issue on a 3-disk-RAID1, one disk failed with its
SB unreadable. Now with this patch user will have a choice to delete
the device using devid.

The other method we could do, is to match the input device_path
to the available device_paths with in the kernel. But that won't
work in all the cases, like what if user provided mapper path
when the path within the kernel is a non-mapper path.

This patch depends on the below kernel patch for the new feature to work,
however it will fail-back to the old interface for the kernel without the
patch

  Btrfs: Introduce device delete by devid

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/Documentation/btrfs-device.asciidoc b/Documentation/btrfs-device.asciidoc
index d6d55af..edd9b98 100644 (file)
--- a/Documentation/btrfs-device.asciidoc
+++ b/Documentation/btrfs-device.asciidoc
@@ -74,10 +74,10 @@ do not perform discard by default
 -f|--force::::
 force overwrite of existing filesystem on the given disk(s)
 
-*remove* <dev> [<dev>...] <path>::
+*remove* <dev>|<devid> [<dev>|<devid>...] <path>::
 Remove device(s) from a filesystem identified by <path>.
 
-*delete* <dev> [<dev>...] <path>::
+*delete* <dev>|<devid> [<dev>|<devid>...] <path>::
 Alias of remove kept for backward compatibility
 
 *ready* <device>::

diff --git a/cmds-device.c b/cmds-device.c
index 9906d4a..b17b6c6 100644 (file)
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -159,20 +159,46 @@ static int _cmd_device_remove(int argc, char **argv,
 
        for(i = optind; i < argc - 1; i++) {
                struct  btrfs_ioctl_vol_args arg;
+               struct btrfs_ioctl_vol_args_v2 argv2 = {0};
+               int is_devid = 0;
                int     res;
 
-               if (is_block_device(argv[i]) != 1 && strcmp(argv[i], "missing")) {
+               if (string_is_numerical(argv[i])) {
+                       argv2.devid = arg_strtou64(argv[i]);
+                       argv2.flags = BTRFS_DEVICE_SPEC_BY_ID;
+                       is_devid = 1;
+               } else if (is_block_device(argv[i]) == 1 ||
+                               strcmp(argv[i], "missing") == 0) {
+                       strncpy_null(argv2.name, argv[i]);
+               } else {
                        error("not a block device: %s", argv[i]);
                        ret++;
                        continue;
                }
-               memset(&arg, 0, sizeof(arg));
-               strncpy_null(arg.name, argv[i]);
+
                /*
                 * Positive values are from BTRFS_ERROR_DEV_*,
                 * otherwise it's a generic error, one of errnos
                 */
-               res = ioctl(fdmnt, BTRFS_IOC_RM_DEV, &arg);
+               res = ioctl(fdmnt, BTRFS_IOC_RM_DEV_V2, &argv2);
+
+               /*
+                * If BTRFS_IOC_RM_DEV_V2 is not supported we get ENOTTY and if
+                * argv2.flags includes a flag which kernel doesn't understand then
+                * we shall get EOPNOTSUPP
+                */
+               if (res < 0 && (errno == ENOTTY || errno == EOPNOTSUPP)) {
+                       if (is_devid) {
+                               error("device delete by id failed: %s",
+                                                       strerror(errno));
+                               ret++;
+                               continue;
+                       }
+                       memset(&arg, 0, sizeof(arg));
+                       strncpy_null(arg.name, argv[i]);
+                       res = ioctl(fdmnt, BTRFS_IOC_RM_DEV, &arg);
+               }
+
                if (res) {
                        const char *msg;
 
@@ -180,8 +206,13 @@ static int _cmd_device_remove(int argc, char **argv,
                                msg = btrfs_err_str(res);
                        else
                                msg = strerror(errno);
-                       error("error removing device '%s': %s",
-                               argv[i], msg);
+                       if (is_devid) {
+                               error("error removing devid %llu: %s",
+                                       (unsigned long long)argv2.devid, msg);
+                       } else {
+                               error("error removing device '%s': %s",
+                                       argv[i], msg);
+                       }
                        ret++;
                }
        }
@@ -191,7 +222,7 @@ static int _cmd_device_remove(int argc, char **argv,
 }
 
 static const char * const cmd_device_remove_usage[] = {
-       "btrfs device remove <device> [<device>...] <path>",
+       "btrfs device remove <device>|<devid> [<device>|<devid>...] <path>",
        "Remove a device from a filesystem",
        NULL
 };
@@ -202,7 +233,7 @@ static int cmd_device_remove(int argc, char **argv)
 }
 
 static const char * const cmd_device_delete_usage[] = {
-       "btrfs device delete <device> [<device>...] <path>",
+       "btrfs device delete <device>|<devid> [<device>|<devid>...] <path>",
        "Remove a device from a filesystem",
        NULL
 };

diff --git a/ioctl.h b/ioctl.h
index 771da23..cab9ec2 100644 (file)
--- a/ioctl.h
+++ b/ioctl.h
@@ -45,6 +45,14 @@ struct btrfs_ioctl_vol_args {
 #define BTRFS_SUBVOL_CREATE_ASYNC      (1ULL << 0)
 #define BTRFS_SUBVOL_RDONLY            (1ULL << 1)
 #define BTRFS_SUBVOL_QGROUP_INHERIT    (1ULL << 2)
+#define BTRFS_DEVICE_SPEC_BY_ID                (1ULL << 3)
+
+#define BTRFS_VOL_ARG_V2_FLAGS_SUPPORTED               \
+                       (BTRFS_SUBVOL_CREATE_ASYNC |    \
+                       BTRFS_SUBVOL_RDONLY |           \
+                       BTRFS_SUBVOL_QGROUP_INHERIT |   \
+                       BTRFS_DEVICE_SPEC_BY_ID)
+
 #define BTRFS_FSID_SIZE 16
 #define BTRFS_UUID_SIZE 16
 
@@ -84,7 +92,10 @@ struct btrfs_ioctl_vol_args_v2 {
                };
                __u64 unused[4];
        };
-       char name[BTRFS_SUBVOL_NAME_MAX + 1];
+       union {
+               char name[BTRFS_SUBVOL_NAME_MAX + 1];
+               u64 devid;
+       };
 };
 
 /*
@@ -709,6 +720,8 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
                                   struct btrfs_ioctl_feature_flags[2])
 #define BTRFS_IOC_GET_SUPPORTED_FEATURES _IOR(BTRFS_IOCTL_MAGIC, 57, \
                                   struct btrfs_ioctl_feature_flags[3])
+#define BTRFS_IOC_RM_DEV_V2    _IOW(BTRFS_IOCTL_MAGIC, 58, \
+                                  struct btrfs_ioctl_vol_args_v2)
 #ifdef __cplusplus
 }
 #endif