[RFC PATCH -v4 08/14] fsnotify: parent event notification

From: Eric Paris
Date: Fri Dec 12 2008 - 16:54:16 EST

inotify and dnotify both use a similar parent notification mechanism. We
add a generic parent notification mechanism to fsnotify for both of these
to use. This new machanism also adds the dentry flag optimization which
exists for inotify to dnotify.

Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>
---

fs/notify/inode_mark.c | 2 +
include/linux/dcache.h | 3 +
include/linux/fsnotify.h | 103 +++++++++++++++++++++++++++++++++++++-
include/linux/fsnotify_backend.h | 5 ++
4 files changed, 109 insertions(+), 4 deletions(-)

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index c68adff..339a368 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -255,6 +255,8 @@ void fsnotify_recalc_inode_mask(struct inode *inode)
}
inode->i_fsnotify_mask = new_mask;
spin_unlock(&inode->i_lock);
+
+ fsnotify_update_dentry_child_flags(inode);
}


diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index a37359d..2f7f646 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -175,7 +175,8 @@ d_iput: no no no yes
#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
#define DCACHE_UNHASHED 0x0010

-#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */
+#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched by inotify */
+#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0040 /* Parent inode is watched by some fsnotify listener */

extern spinlock_t dcache_lock;
extern seqlock_t rename_lock;
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index c2ed916..971ada9 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -16,14 +16,93 @@
#include <linux/fsnotify_backend.h>
#include <linux/audit.h>

+static inline int fsnotify_inode_watches_children(struct inode *inode)
+{
+ if (inode->i_fsnotify_mask & (FS_EVENTS_WITH_CHILD << 32))
+ return 1;
+ return 0;
+}
+
+/*
+ * Get child dentry flag into synch with parent inode.
+ * Flag should always be clear for negative dentrys.
+ */
+static inline void fsnotify_update_dentry_child_flags(struct inode *inode)
+{
+ struct dentry *alias;
+ int watched = fsnotify_inode_watches_children(inode);
+
+ spin_lock(&dcache_lock);
+ list_for_each_entry(alias, &inode->i_dentry, d_alias) {
+ struct dentry *child;
+
+ list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
+ if (!child->d_inode)
+ continue;
+
+ spin_lock(&child->d_lock);
+ if (watched)
+ child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+ else
+ child->d_flags &=~DCACHE_FSNOTIFY_PARENT_WATCHED;
+ spin_unlock(&child->d_lock);
+ }
+ }
+ spin_unlock(&dcache_lock);
+}
+
/*
* fsnotify_d_instantiate - instantiate a dentry for inode
* Called with dcache_lock held.
*/
-static inline void fsnotify_d_instantiate(struct dentry *entry,
- struct inode *inode)
+static inline void fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
+{
+ struct dentry *parent;
+ struct inode *p_inode;
+
+ if (!inode)
+ return;
+
+ spin_lock(&dentry->d_lock);
+ parent = dentry->d_parent;
+ p_inode = parent->d_inode;
+
+ if (p_inode && fsnotify_inode_watches_children(p_inode))
+ dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+ spin_unlock(&dentry->d_lock);
+
+ /* call the legacy inotify shit */
+ inotify_d_instantiate(dentry, inode);
+}
+
+/* Notify this dentry's parent about a child's events. */
+static inline void fsnotify_parent(struct dentry *dentry, __u64 orig_mask)
{
- inotify_d_instantiate(entry, inode);
+ struct dentry *parent;
+ struct inode *p_inode;
+ __u64 mask;
+
+ if (!(dentry->d_flags | DCACHE_FSNOTIFY_PARENT_WATCHED))
+ return;
+
+ /* we are notifying a parent so come up with the new mask which
+ * specifies these are events which came from a child. */
+ mask = (orig_mask & FS_EVENTS_WITH_CHILD) << 32;
+ /* need to remember if the child was a dir */
+ mask |= (orig_mask & FS_IN_ISDIR);
+
+ spin_lock(&dentry->d_lock);
+ parent = dentry->d_parent;
+ p_inode = parent->d_inode;
+
+ if (p_inode && (p_inode->i_fsnotify_mask & mask)) {
+ dget(parent);
+ spin_unlock(&dentry->d_lock);
+ fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE);
+ dput(parent);
+ } else {
+ spin_unlock(&dentry->d_lock);
+ }
}

/*
@@ -32,6 +111,14 @@ static inline void fsnotify_d_instantiate(struct dentry *entry,
*/
static inline void fsnotify_d_move(struct dentry *entry)
{
+ struct dentry *parent;
+
+ parent = entry->d_parent;
+ if (fsnotify_inode_watches_children(parent->d_inode))
+ entry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+ else
+ entry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
+
inotify_d_move(entry);
}

@@ -96,6 +183,8 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
isdir = IN_ISDIR;
dnotify_parent(dentry, DN_DELETE);
inotify_dentry_parent_queue_event(dentry, IN_DELETE|isdir, 0, dentry->d_name.name);
+
+ fsnotify_parent(dentry, FS_DELETE|isdir);
}

/*
@@ -186,6 +275,7 @@ static inline void fsnotify_access(struct file *file)
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);

+ fsnotify_parent(dentry, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE);
}

@@ -205,6 +295,7 @@ static inline void fsnotify_modify(struct file *file)
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);

+ fsnotify_parent(dentry, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE);
}

@@ -220,6 +311,7 @@ static inline void fsnotify_open_exec(struct file *file)
inotify_dentry_parent_queue_event(dentry, IN_ACCESS, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, IN_ACCESS, 0, NULL, NULL);

+ fsnotify_parent(dentry, FS_ACCESS);
fsnotify(inode, FS_ACCESS, file, FSNOTIFY_EVENT_FILE);
}

@@ -238,6 +330,7 @@ static inline void fsnotify_open(struct file *file)
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);

+ fsnotify_parent(dentry, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE);
}

@@ -258,6 +351,7 @@ static inline void fsnotify_close(struct file *file)
inotify_dentry_parent_queue_event(dentry, mask, 0, name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);

+ fsnotify_parent(dentry, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE);
}

@@ -275,6 +369,7 @@ static inline void fsnotify_xattr(struct dentry *dentry)
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);

+ fsnotify_parent(dentry, mask);
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
}

@@ -325,6 +420,8 @@ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
inotify_inode_queue_event(inode, in_mask, 0, NULL, NULL);
inotify_dentry_parent_queue_event(dentry, in_mask, 0,
dentry->d_name.name);
+
+ fsnotify_parent(dentry, in_mask);
fsnotify(inode, in_mask, inode, FSNOTIFY_EVENT_INODE);
}
}
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 0482a14..3e4ac24 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -65,6 +65,11 @@
#define FS_DN_RENAME 0x1000000000000000ull /* file renamed */
#define FS_DN_MULTISHOT 0x2000000000000000ull /* dnotify multishot */

+#define FS_EVENTS_WITH_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
+ FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
+ FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
+ FS_DELETE)
+
/* when calling fsnotify tell it if the data is a file, dentry, or inode */
#define FSNOTIFY_EVENT_FILE 1
#define FSNOTIFY_EVENT_INODE 2

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