Unionfs: release lower resources on successful rmdir

This patch prevents those resources from lingering around until memory
pressure would have forced them out.  The patch also properly handles
directories that have been rmdir'ed which are still some process's cwd.

CC: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index 55bf4db33a4d147912682281a5a91efab8a102c0..18a68cf2d3bc5613e97681ddfdc68634c523def1 100644 (file)
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -932,7 +932,8 @@ static int unionfs_permission(struct inode *inode, int mask,
                 * dentry+inode.  This should be equivalent to issuing
                 * __unionfs_d_revalidate_chain on nd.dentry here.
                 */
-               err = -ESTALE;  /* force revalidate */
+               if (is_file)    /* dirs can be unlinked but chdir'ed to */
+                       err = -ESTALE;  /* force revalidate */
                goto out;
        }
 

diff --git a/fs/unionfs/mmap.c b/fs/unionfs/mmap.c
index 9fa5751b804ed0348722c07b880da3e046058440..5b29477098c5d6532d1903c79988e8840a5a7435 100644 (file)
--- a/fs/unionfs/mmap.c
+++ b/fs/unionfs/mmap.c
@@ -150,8 +150,11 @@ static int unionfs_writepages(struct address_space *mapping,
        struct inode *inode;
 
        inode = mapping->host;
+       if (ibstart(inode) < 0 && ibend(inode) < 0)
+               goto out;
        lower_inode = unionfs_lower_inode(inode);
-       BUG_ON(!lower_inode);
+       if (!lower_inode)
+               goto out;
 
         if (mapping->backing_dev_info->memory_backed)
                goto out;

diff --git a/fs/unionfs/unlink.c b/fs/unionfs/unlink.c
index a8de6725965162c273f9461826020fe4c3992172..f65245dcb4f94264217d4b5991a5ec3e7a506558 100644 (file)
--- a/fs/unionfs/unlink.c
+++ b/fs/unionfs/unlink.c
@@ -148,6 +148,7 @@ int unionfs_rmdir(struct inode *dir, struct dentry *dentry)
 {
        int err = 0;
        struct unionfs_dir_state *namelist = NULL;
+       int dstart, dend;
 
        unionfs_read_lock(dentry->d_sb);
        unionfs_lock_dentry(dentry);
@@ -164,28 +165,50 @@ int unionfs_rmdir(struct inode *dir, struct dentry *dentry)
                goto out;
 
        err = unionfs_rmdir_first(dir, dentry, namelist);
+       dstart = dbstart(dentry);
+       dend = dbend(dentry);
        /* create whiteout */
        if (!err) {
-               err = create_whiteout(dentry, dbstart(dentry));
+               err = create_whiteout(dentry, dstart);
        } else {
                int new_err;
 
-               if (dbstart(dentry) == 0)
+               if (dstart == 0)
                        goto out;
 
                /* exit if the error returned was NOT -EROFS */
                if (!IS_COPYUP_ERR(err))
                        goto out;
 
-               new_err = create_whiteout(dentry, dbstart(dentry) - 1);
+               new_err = create_whiteout(dentry, dstart - 1);
                if (new_err != -EEXIST)
                        err = new_err;
        }
 
 out:
-       /* call d_drop so the system "forgets" about us */
-       if (!err)
+       /*
+        * Drop references to lower dentry/inode so storage space for them
+        * can be reclaimed.  Then, call d_drop so the system "forgets"
+        * about us.
+        */
+       if (!err) {
+               struct inode *inode = dentry->d_inode;
+               BUG_ON(!inode);
+               iput(unionfs_lower_inode_idx(inode, dstart));
+               unionfs_set_lower_inode_idx(inode, dstart, NULL);
+               dput(unionfs_lower_dentry_idx(dentry, dstart));
+               unionfs_set_lower_dentry_idx(dentry, dstart, NULL);
+               /*
+                * If the last directory is unlinked, then mark istart/end
+                * as -1, (to maintain the invariant that if there are no
+                * lower objects, then branch index start and end are set to
+                * -1).
+                */
+               if (!unionfs_lower_inode_idx(inode, dstart) &&
+                   !unionfs_lower_inode_idx(inode, dend))
+                       ibstart(inode) = ibend(inode) = -1;
                d_drop(dentry);
+       }
 
        if (namelist)
                free_rdstate(namelist);