lkml.org 
[lkml]   [2009]   [Apr]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH -V2 12/13] fsnotify: handle filesystem unmounts with fsnotify marks
On Fri, 27 Mar 2009 16:06:11 -0400
Eric Paris <eparis@redhat.com> wrote:

> When an fs is unmounted with an fsnotify mark entry attached to one of its
> inodes we need to destroy that mark entry and we also (like inotify) send
> an unmount event.
>
>
> ...
>
> +/**
> + * fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
> + * @list: list of inodes being unmounted (sb->s_inodes)
> + *
> + * Called with inode_lock held, protecting the unmounting super block's list
> + * of inodes, and with iprune_mutex held, keeping shrink_icache_memory() at bay.
> + * We temporarily drop inode_lock, however, and CAN block.
> + */
> +void fsnotify_unmount_inodes(struct list_head *list)
> +{
> + struct inode *inode, *next_i, *need_iput = NULL;
> +
> + list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
> + struct inode *need_iput_tmp;
> +
> + /*
> + * If i_count is zero, the inode cannot have any watches and
> + * doing an __iget/iput with MS_ACTIVE clear would actually
> + * evict all inodes with zero i_count from icache which is
> + * unnecessarily violent and may in fact be illegal to do.
> + */
> + if (!atomic_read(&inode->i_count))
> + continue;
> +
> + /*
> + * We cannot __iget() an inode in state I_CLEAR, I_FREEING, or
> + * I_WILL_FREE which is fine because by that point the inode
> + * cannot have any associated watches.
> + */
> + if (inode->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))
> + continue;
> +
> + need_iput_tmp = need_iput;
> + need_iput = NULL;
> +
> + /* In case fsnotify_inode_delete() drops a reference. */
> + if (inode != need_iput_tmp)
> + __iget(inode);
> + else
> + need_iput_tmp = NULL;
> +
> + /* In case the dropping of a reference would nuke next_i. */
> + if ((&next_i->i_sb_list != list) &&
> + atomic_read(&next_i->i_count) &&
> + !(next_i->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))) {
> + __iget(next_i);
> + need_iput = next_i;
> + }
> +
> + /*
> + * We can safely drop inode_lock here because we hold
> + * references on both inode and next_i. Also no new inodes
> + * will be added since the umount has begun. Finally,
> + * iprune_mutex keeps shrink_icache_memory() away.
> + */
> + spin_unlock(&inode_lock);
> +
> + if (need_iput_tmp)
> + iput(need_iput_tmp);

iput(NULL) is legal.

> + /* for each watch, send FS_UNMOUNT and then remove it */
> + fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
> +
> + fsnotify_inode_delete(inode);
> +
> + iput(inode);
> +
> + spin_lock(&inode_lock);
> + }
> +}
> +EXPORT_SYMBOL_GPL(fsnotify_unmount_inodes);

Why is it exported?


\
 
 \ /
  Last update: 2009-04-08 01:19    [W:0.406 / U:0.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site