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    Subject[RFC PATCH -v4 08/14] fsnotify: parent event notification
    Date
    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@redhat.com>
    ---

    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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