btrfs: add a flags argument to LOGICAL_INO and call it LOGICAL_INO_V2

Now that check_extent_in_eb()'s extent offset filter can be turned off,
we need a way to do it from userspace.

Add a 'flags' field to the btrfs_logical_ino_args structure to disable extent
offset filtering, taking the place of one of the reserved[] fields.

Previous versions of LOGICAL_INO neglected to check whether any of the
reserved fields have non-zero values.  Assigning meaning to those fields
now may change the behavior of existing programs that left these fields
uninitialized.

To avoid any surprises, define a new ioctl LOGICAL_INO_V2 which uses
the same argument layout as LOGICAL_INO, but uses one of the reserved
fields for flags.  The V2 ioctl explicitly checks that unsupported flag
bits are zero so that userspace can probe for future feature bits as
they are defined.  If the other reserved fields are used in the future,
one of the remaining flag bits could specify that the other reserved
fields are valid, so we don't need to check those for now.

Since the memory layouts and behavior of the two ioctls' arguments
are almost identical, there is no need for a separate function for
logical_to_ino_v2 (contrast with tree_search_v2 vs tree_search).
A version parameter and an 'if' statement will suffice.

Now that we have a flags field in logical_ino_args, add a flag
BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET to get the behavior we want,
and pass it down the stack to iterate_inodes_from_logical.

Signed-off-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b7de325680827b7a8abb7c33c5732160329a5c81..2bc3a9588d1d24f1b31a427b5774d4ed15d4c903 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4536,13 +4536,14 @@ static int build_ino_list(u64 inum, u64 offset, u64 root, void *ctx)
 }
 
 static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
-                                       void __user *arg)
+                                       void __user *arg, int version)
 {
        int ret = 0;
        int size;
        struct btrfs_ioctl_logical_ino_args *loi;
        struct btrfs_data_container *inodes = NULL;
        struct btrfs_path *path = NULL;
+       bool ignore_offset;
 
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
@@ -4551,6 +4552,17 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
        if (IS_ERR(loi))
                return PTR_ERR(loi);
 
+       if (version == 1) {
+               ignore_offset = false;
+       } else {
+               /* Only accept flags we have defined so far */
+               if (loi->flags & ~(BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET)) {
+                       ret = -EINVAL;
+                       goto out_loi;
+               }
+               ignore_offset = loi->flags & BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET;
+       }
+
        path = btrfs_alloc_path();
        if (!path) {
                ret = -ENOMEM;
@@ -4566,7 +4578,7 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
        }
 
        ret = iterate_inodes_from_logical(loi->logical, fs_info, path,
-                                         build_ino_list, inodes, false);
+                                         build_ino_list, inodes, ignore_offset);
        if (ret == -EINVAL)
                ret = -ENOENT;
        if (ret < 0)
@@ -4580,6 +4592,7 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
 out:
        btrfs_free_path(path);
        kvfree(inodes);
+out_loi:
        kfree(loi);
 
        return ret;
@@ -5550,7 +5563,9 @@ long btrfs_ioctl(struct file *file, unsigned int
        case BTRFS_IOC_INO_PATHS:
                return btrfs_ioctl_ino_to_path(root, argp);
        case BTRFS_IOC_LOGICAL_INO:
-               return btrfs_ioctl_logical_to_ino(fs_info, argp);
+               return btrfs_ioctl_logical_to_ino(fs_info, argp, 1);
+       case BTRFS_IOC_LOGICAL_INO_V2:
+               return btrfs_ioctl_logical_to_ino(fs_info, argp, 2);
        case BTRFS_IOC_SPACE_INFO:
                return btrfs_ioctl_space_info(fs_info, argp);
        case BTRFS_IOC_SYNC: {

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 378230c163d5ecdf87a1d5062c8a431a7c9c5c45..0b3de597e04f08e343b50ac737e2e718e07b1d2f 100644 (file)
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -608,10 +608,14 @@ struct btrfs_ioctl_ino_path_args {
 struct btrfs_ioctl_logical_ino_args {
        __u64                           logical;        /* in */
        __u64                           size;           /* in */
-       __u64                           reserved[4];
+       __u64                           flags;          /* in, v2 only */
+       __u64                           reserved[3];
        /* struct btrfs_data_container  *inodes;        out   */
        __u64                           inodes;
 };
+/* Return every ref to the extent, not just those containing logical block.
+ * Requires logical == extent bytenr. */
+#define BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET   (1ULL << 0)
 
 enum btrfs_dev_stat_values {
        /* disk I/O failure stats */
@@ -835,5 +839,7 @@ enum btrfs_err_code {
                                   struct btrfs_ioctl_feature_flags[3])
 #define BTRFS_IOC_RM_DEV_V2 _IOW(BTRFS_IOCTL_MAGIC, 58, \
                                   struct btrfs_ioctl_vol_args_v2)
+#define BTRFS_IOC_LOGICAL_INO_V2 _IOWR(BTRFS_IOCTL_MAGIC, 59, \
+                                       struct btrfs_ioctl_logical_ino_args)
 
 #endif /* _UAPI_LINUX_BTRFS_H */