btrfs: simplify generation check in btrfs_get_dentry

Callers that pass non-zero generation always want to perform the generation check, we can simply encode that in one parameter and drop check_generation. Add function documentation. Reviewed-by: Josef Bacik <[email protected]> Signed-off-by: David Sterba <[email protected]>
torvalds · Dec 5, 2022 · b307f06 · b307f06
1 parent 63a7cb1
commit b307f06
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Showing 3 changed files with 19 additions and 9 deletions.
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
@@ -57,9 +57,20 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
  return type;
 }
 
+/*
+ * Read dentry of inode with @objectid from filesystem root @root_objectid.
+ *
+ * @sb: the filesystem super block
+ * @objectid: inode objectid
+ * @root_objectid: object id of the subvolume root where to look up the inode
+ * @generation: optional, if not zero, verify that the found inode
+ * generation matches
+ *
+ * Return dentry alias for the inode, otherwise an error. In case the
+ * generation does not match return ESTALE.
+ */
 struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
- u64 root_objectid, u64 generation,
- int check_generation)
+ u64 root_objectid, u64 generation)
 {
  struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  struct btrfs_root *root;
@@ -77,7 +88,7 @@ struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
  if (IS_ERR(inode))
  return ERR_CAST(inode);
 
- if (check_generation && generation != inode->i_generation) {
+ if (generation != 0 && generation != inode->i_generation) {
  iput(inode);
  return ERR_PTR(-ESTALE);
  }
@@ -106,7 +117,7 @@ static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
  objectid = fid->parent_objectid;
  generation = fid->parent_gen;
 
- return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
+ return btrfs_get_dentry(sb, objectid, root_objectid, generation);
 }
 
 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
@@ -128,7 +139,7 @@ static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
  root_objectid = fid->root_objectid;
  generation = fid->gen;
 
- return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
+ return btrfs_get_dentry(sb, objectid, root_objectid, generation);
 }
 
 struct dentry *btrfs_get_parent(struct dentry *child)
@@ -188,7 +199,7 @@ struct dentry *btrfs_get_parent(struct dentry *child)
 
  if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
  return btrfs_get_dentry(fs_info->sb, key.objectid,
- found_key.offset, 0, 0);
+ found_key.offset, 0);
  }
 
  return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root));

diff --git a/fs/btrfs/export.h b/fs/btrfs/export.h
@@ -19,8 +19,7 @@ struct btrfs_fid {
 } __attribute__ ((packed));
 
 struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
- u64 root_objectid, u64 generation,
- int check_generation);
+ u64 root_objectid, u64 generation);
 struct dentry *btrfs_get_parent(struct dentry *child);
 
 #endif
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
@@ -3274,7 +3274,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 
  dentry = btrfs_get_dentry(fs_info->sb,
  BTRFS_FIRST_FREE_OBJECTID,
- vol_args2->subvolid, 0, 0);
+ vol_args2->subvolid, 0);
  if (IS_ERR(dentry)) {
  err = PTR_ERR(dentry);
  goto out_drop_write;