Don't pass inode to ->d_hash() and ->d_compare()
Instances either don't look at it at all (the majority of cases) or
only want it to find the superblock (which can be had as dentry->d_sb).
A few cases that want more are actually safe with dentry->d_inode -
the only precaution needed is the check that it hadn't been replaced with
NULL by rmdir() or by overwriting rename(), which case should be simply
treated as cache miss.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index bdd82b2..f94a362 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -11,10 +11,8 @@
prototypes:
int (*d_revalidate)(struct dentry *, unsigned int);
int (*d_weak_revalidate)(struct dentry *, unsigned int);
- int (*d_hash)(const struct dentry *, const struct inode *,
- struct qstr *);
- int (*d_compare)(const struct dentry *, const struct inode *,
- const struct dentry *, const struct inode *,
+ int (*d_hash)(const struct dentry *, struct qstr *);
+ int (*d_compare)(const struct dentry *, const struct dentry *,
unsigned int, const char *, const struct qstr *);
int (*d_delete)(struct dentry *);
void (*d_release)(struct dentry *);
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 4a35f66..51ba44e 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -901,10 +901,8 @@
struct dentry_operations {
int (*d_revalidate)(struct dentry *, unsigned int);
int (*d_weak_revalidate)(struct dentry *, unsigned int);
- int (*d_hash)(const struct dentry *, const struct inode *,
- struct qstr *);
- int (*d_compare)(const struct dentry *, const struct inode *,
- const struct dentry *, const struct inode *,
+ int (*d_hash)(const struct dentry *, struct qstr *);
+ int (*d_compare)(const struct dentry *, const struct dentry *,
unsigned int, const char *, const struct qstr *);
int (*d_delete)(const struct dentry *);
void (*d_release)(struct dentry *);
@@ -949,25 +947,24 @@
d_hash: called when the VFS adds a dentry to the hash table. The first
dentry passed to d_hash is the parent directory that the name is
- to be hashed into. The inode is the dentry's inode.
+ to be hashed into.
Same locking and synchronisation rules as d_compare regarding
what is safe to dereference etc.
d_compare: called to compare a dentry name with a given name. The first
dentry is the parent of the dentry to be compared, the second is
- the parent's inode, then the dentry and inode (may be NULL) of the
- child dentry. len and name string are properties of the dentry to be
- compared. qstr is the name to compare it with.
+ the child dentry. len and name string are properties of the dentry
+ to be compared. qstr is the name to compare it with.
Must be constant and idempotent, and should not take locks if
- possible, and should not or store into the dentry or inodes.
- Should not dereference pointers outside the dentry or inodes without
+ possible, and should not or store into the dentry.
+ Should not dereference pointers outside the dentry without
lots of care (eg. d_parent, d_inode, d_name should not be used).
However, our vfsmount is pinned, and RCU held, so the dentries and
inodes won't disappear, neither will our sb or filesystem module.
- ->i_sb and ->d_sb may be used.
+ ->d_sb may be used.
It is a tricky calling convention because it needs to be called under
"rcu-walk", ie. without any locks or references on things.