On Mon 08-09-14 16:01:56, Andrey Vagin wrote:
> Currently watchers are removed in dentry_iput(), if n_link is zero.
> But other detries can be linked with this inode. For example if we
> create two hard links, open the first one and set a watcher on the
> second one. Then if we remove both links, the watcher will be removed.
> But we will have the alive file descriptor, which allows us to generate
> more events.
>
> With this patch, watchers will be removed, only if nlink is zero and
> i_dentry list is empty.
>
> Look at a following example:
>
> fd = inotify_init1(IN_NONBLOCK);
> deleted = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0666);
> link(path, path_link);
>
> wd_deleted = inotify_add_watch(fd, path_link, IN_ALL_EVENTS);
>
> unlink(path);
> unlink(path_link);
>
> printf(" --- unlink\n");
> read_evetns(fd);
>
> close(deleted);
> printf(" --- close\n");
> read_evetns(fd);
>
> Without this patch:
> --- unlink
> 4 (IN_ATTRIB)
> 400 (IN_DELETE_SELF)
> 8000 (IN_IGNORED)
> --- close
> FAIL
>
> With this patch:
> --- unlink
> 4 (IN_ATTRIB)
> 400 (IN_DELETE_SELF)
> --- close
> 8 (IN_CLOSE_WRITE)
> 400 (IN_DELETE_SELF)
> 8000 (IN_IGNORED)
> PASS
>
> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: John McCutchan <john@xxxxxxxxxxxxxxxxx>
> Cc: Robert Love <rlove@xxxxxxxxx>
> Cc: Eric Paris <eparis@xxxxxxxxxxxxxx>
> Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> Signed-off-by: Andrey Vagin <avagin@xxxxxxxxxx>
OK, looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/dcache.c | 10 ++++++++--
> include/linux/fsnotify.h | 5 +++--
> 2 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index d30ce69..fb1ee58 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -279,13 +279,16 @@ static void dentry_iput(struct dentry * dentry)
> __releases(dentry->d_inode->i_lock)
> {
> struct inode *inode = dentry->d_inode;
> + bool last_dentry;
> +
> if (inode) {
> dentry->d_inode = NULL;
> hlist_del_init(&dentry->d_alias);
> + last_dentry = hlist_empty(&inode->i_dentry);
> spin_unlock(&dentry->d_lock);
> spin_unlock(&inode->i_lock);
> if (!inode->i_nlink)
> - fsnotify_inoderemove(inode);
> + fsnotify_inoderemove(inode, last_dentry);
> if (dentry->d_op && dentry->d_op->d_iput)
> dentry->d_op->d_iput(dentry, inode);
> else
> @@ -304,14 +307,17 @@ static void dentry_unlink_inode(struct dentry * dentry)
> __releases(dentry->d_inode->i_lock)
> {
> struct inode *inode = dentry->d_inode;
> + bool last_dentry;
> +
> __d_clear_type(dentry);
> dentry->d_inode = NULL;
> hlist_del_init(&dentry->d_alias);
> dentry_rcuwalk_barrier(dentry);
> + last_dentry = hlist_empty(&inode->i_dentry);
> spin_unlock(&dentry->d_lock);
> spin_unlock(&inode->i_lock);
> if (!inode->i_nlink)
> - fsnotify_inoderemove(inode);
> + fsnotify_inoderemove(inode, last_dentry);
> if (dentry->d_op && dentry->d_op->d_iput)
> dentry->d_op->d_iput(dentry, inode);
> else
> diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
> index 1c804b0..63dae9d 100644
> --- a/include/linux/fsnotify.h
> +++ b/include/linux/fsnotify.h
> @@ -144,10 +144,11 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
> /*
> * fsnotify_inoderemove - an inode is going away
> */
> -static inline void fsnotify_inoderemove(struct inode *inode)
> +static inline void fsnotify_inoderemove(struct inode *inode, bool delete)
> {
> fsnotify(inode, FS_DELETE_SELF, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
> - __fsnotify_inode_delete(inode);
> + if (delete)
> + __fsnotify_inode_delete(inode);
> }
>
> /*
> --
> 1.9.3
>
> --
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--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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