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btrfs: simplify generation check in btrfs_get_dentry

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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 <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2022-10-18 16:06:38 +02:00
parent 63a7cb1307
commit b307f06d37
3 changed files with 19 additions and 9 deletions
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23
fs/btrfs/export.c
View File

@ -57,9 +57,20 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
return type; 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, struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
u64 root_objectid, u64 generation, u64 root_objectid, u64 generation)
int check_generation)
{ {
struct btrfs_fs_info *fs_info = btrfs_sb(sb); struct btrfs_fs_info *fs_info = btrfs_sb(sb);
struct btrfs_root *root; struct btrfs_root *root;
@ -77,7 +88,7 @@ struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
if (IS_ERR(inode)) if (IS_ERR(inode))
return ERR_CAST(inode); return ERR_CAST(inode);
if (check_generation && generation != inode->i_generation) { if (generation != 0 && generation != inode->i_generation) {
iput(inode); iput(inode);
return ERR_PTR(-ESTALE); 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; objectid = fid->parent_objectid;
generation = fid->parent_gen; 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, 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; root_objectid = fid->root_objectid;
generation = fid->gen; 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) 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) { if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
return btrfs_get_dentry(fs_info->sb, key.objectid, 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)); return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root));

3
fs/btrfs/export.h
View File

@ -19,8 +19,7 @@ struct btrfs_fid {
} __attribute__ ((packed)); } __attribute__ ((packed));
struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
u64 root_objectid, u64 generation, u64 root_objectid, u64 generation);
int check_generation);
struct dentry *btrfs_get_parent(struct dentry *child); struct dentry *btrfs_get_parent(struct dentry *child);
#endif #endif

2
fs/btrfs/ioctl.c
View File

@ -3274,7 +3274,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
dentry = btrfs_get_dentry(fs_info->sb, dentry = btrfs_get_dentry(fs_info->sb,
BTRFS_FIRST_FREE_OBJECTID, BTRFS_FIRST_FREE_OBJECTID,
vol_args2->subvolid, 0, 0); vol_args2->subvolid, 0);
if (IS_ERR(dentry)) { if (IS_ERR(dentry)) {
err = PTR_ERR(dentry); err = PTR_ERR(dentry);
goto out_drop_write; goto out_drop_write;