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Subject[PATCH 1/4] vfs: add d_prune dentry operation
Date
This adds a d_prune dentry operation that is called by the VFS prior to
pruning (i.e. unhashing and killing) a hashed dentry from the dcache. This
will be used by Ceph to maintain a flag indicating whether the complete
contents of a directory are contained in the dcache, allowing it to satisfy
lookups and readdir without addition server communication.

Signed-off-by: Sage Weil <sage@newdream.net>
---
Documentation/filesystems/Locking | 1 +
fs/dcache.c | 8 ++++++++
include/linux/dcache.h | 3 +++
3 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 4471a41..30de5ef 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -29,6 +29,7 @@ d_hash no no no maybe
d_compare: yes no no maybe
d_delete: no yes no no
d_release: no no yes no
+d_prune: no yes no no
d_iput: no no yes no
d_dname: no no no no
d_automount: no no yes no
diff --git a/fs/dcache.c b/fs/dcache.c
index 611ffe9..c54b85e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -690,6 +690,8 @@ static void try_prune_one_dentry(struct dentry *dentry)
spin_unlock(&dentry->d_lock);
return;
}
+ if (dentry->d_flags & DCACHE_OP_PRUNE)
+ dentry->d_op->d_prune(dentry);
dentry = dentry_kill(dentry, 1);
}
}
@@ -896,6 +898,8 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)

/* detach this root from the system */
spin_lock(&dentry->d_lock);
+ if (dentry->d_flags & DCACHE_OP_PRUNE)
+ dentry->d_op->d_prune(dentry);
dentry_lru_del(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
@@ -912,6 +916,8 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
d_u.d_child) {
spin_lock_nested(&loop->d_lock,
DENTRY_D_LOCK_NESTED);
+ if (dentry->d_flags & DCACHE_OP_PRUNE)
+ dentry->d_op->d_prune(dentry);
dentry_lru_del(loop);
__d_drop(loop);
spin_unlock(&loop->d_lock);
@@ -1375,6 +1381,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
dentry->d_flags |= DCACHE_OP_REVALIDATE;
if (op->d_delete)
dentry->d_flags |= DCACHE_OP_DELETE;
+ if (op->d_prune)
+ dentry->d_flags |= DCACHE_OP_PRUNE;

}
EXPORT_SYMBOL(d_set_d_op);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index f958c19..1e83bd8 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -165,6 +165,7 @@ struct dentry_operations {
unsigned int, const char *, const struct qstr *);
int (*d_delete)(const struct dentry *);
void (*d_release)(struct dentry *);
+ void (*d_prune)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
char *(*d_dname)(struct dentry *, char *, int);
struct vfsmount *(*d_automount)(struct path *);
@@ -219,6 +220,8 @@ struct dentry_operations {
#define DCACHE_MANAGED_DENTRY \
(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)

+#define DCACHE_OP_PRUNE 0x80000
+
extern seqlock_t rename_lock;

static inline int dname_external(struct dentry *dentry)
--
1.7.0


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