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btrfs-util: fix creating recursive read-only snapshots

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When creating recursive read-only snapshots we need to mark the snapshot
writable immediately before creating subsnapshots within it, otherwise
the operation for it will fail.
This commit is contained in:
Lennart Poettering 2015-04-22 16:52:53 +02:00
parent 2f4d3bb91f
commit ffb296b2c2
1 changed files with 36 additions and 2 deletions
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38
src/shared/btrfs-util.c
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@ -948,6 +948,7 @@ static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolum
.fd = old_fd,
};
int r;
_cleanup_close_ int subvolume_fd = -1;
assert(old_fd >= 0);
assert(new_fd >= 0);
@ -1028,14 +1029,47 @@ static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolum
if (new_child_fd < 0)
return -errno;
if (flags & BTRFS_SNAPSHOT_READ_ONLY) {
/* If the snapshot is read-only we
* need to mark it writable
* temporarily, to put the subsnapshot
* into place. */
if (subvolume_fd < 0) {
subvolume_fd = openat(new_fd, subvolume, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (subvolume_fd < 0)
return -errno;
}
r = btrfs_subvol_set_read_only_fd(subvolume_fd, false);
if (r < 0)
return r;
}
/* When btrfs clones the subvolumes, child
* subvolumes appear as directories. Remove
* them, so that we can create a new snapshot
* in their place */
if (unlinkat(new_child_fd, p, AT_REMOVEDIR) < 0)
return -errno;
if (unlinkat(new_child_fd, p, AT_REMOVEDIR) < 0) {
int k = -errno;
if (flags & BTRFS_SNAPSHOT_READ_ONLY)
(void) btrfs_subvol_set_read_only_fd(subvolume_fd, true);
return k;
}
r = subvol_snapshot_children(old_child_fd, new_child_fd, p, sh->objectid, flags & ~BTRFS_SNAPSHOT_FALLBACK_COPY);
/* Restore the readonly flag */
if (flags & BTRFS_SNAPSHOT_READ_ONLY) {
int k;
k = btrfs_subvol_set_read_only_fd(subvolume_fd, true);
if (r >= 0 && k < 0)
return k;
}
if (r < 0)
return r;
}