Unionfs: handle whiteouts more efficiently in filldir

If we cache a dirent for file "foo", and then it gets deleted, then we look
for a ".wh.foo" whiteout entry in the same dirent cache.  But our dirent
cache strips the ".wh." prefix, thus looking for an entry named "foo" whose
filldir_node->whiteout should be 1 instead of 0.  In that case, don't
display  an incorrect printk  message that the file system may be corrupt,
but set that filldir_node->whiteout to 1.

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

diff --git a/fs/unionfs/dirfops.c b/fs/unionfs/dirfops.c
index e38ebef7310561cb590face3df4566af453a29eb..a160f5b87e059acfb5fae32a89452e51b0dd23c2 100644 (file)
--- a/fs/unionfs/dirfops.c
+++ b/fs/unionfs/dirfops.c
@@ -53,10 +53,17 @@ static int unionfs_filldir(void *dirent, const char *name, int namelen,
                is_wh_entry = 1;
        }
 
-       found = find_filldir_node(buf->rdstate, name, namelen);
-
-       if (found)
+       found = find_filldir_node(buf->rdstate, name, namelen, is_wh_entry);
+
+       if (found) {
+               /*
+                * If we had non-whiteout entry in dir cache, then mark it
+                * as a whiteout and but leave it in the dir cache.
+                */
+               if (is_wh_entry && !found->whiteout)
+                       found->whiteout = is_wh_entry;
                goto out;
+       }
 
        /* if 'name' isn't a whiteout, filldir it. */
        if (!is_wh_entry) {

diff --git a/fs/unionfs/dirhelper.c b/fs/unionfs/dirhelper.c
index 47f66e9200b78967e386ed3bb7ec3acb00271616..5da1c5adcea6a37cdcc04d95d42a8884ec5ac46e 100644 (file)
--- a/fs/unionfs/dirhelper.c
+++ b/fs/unionfs/dirhelper.c
@@ -158,7 +158,7 @@ static int readdir_util_callback(void *dirent, const char *name, int namelen,
                whiteout = 1;
        }
 
-       found = find_filldir_node(buf->rdstate, name, namelen);
+       found = find_filldir_node(buf->rdstate, name, namelen, whiteout);
        /* If it was found in the table there was a previous whiteout. */
        if (found)
                goto out;

diff --git a/fs/unionfs/rdstate.c b/fs/unionfs/rdstate.c
index 3241380557db1af3955db57ec24f90e2d4953bc2..1ea59e4a36c0632c365d27402cb6b44135113202 100644 (file)
--- a/fs/unionfs/rdstate.c
+++ b/fs/unionfs/rdstate.c
@@ -188,7 +188,8 @@ void free_rdstate(struct unionfs_dir_state *state)
 }
 
 struct filldir_node *find_filldir_node(struct unionfs_dir_state *rdstate,
-                                      const char *name, int namelen)
+                                      const char *name, int namelen,
+                                      int is_whiteout)
 {
        int index;
        unsigned int hash;
@@ -215,10 +216,12 @@ struct filldir_node *find_filldir_node(struct unionfs_dir_state *rdstate,
                        found = 1;
 
                        /*
-                        * if the duplicate is in this branch, then the file
-                        * system is corrupted.
+                        * if a duplicate is found in this branch, and is
+                        * not due to the caller looking for an entry to
+                        * whiteout, then the file system may be corrupted.
                         */
-                       if (unlikely(cursor->bindex == rdstate->bindex))
+                       if (unlikely(!is_whiteout &&
+                                    cursor->bindex == rdstate->bindex))
                                printk(KERN_ERR "unionfs: filldir: possible "
                                       "I/O error: a file is duplicated "
                                       "in the same branch %d: %s\n",

diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
index cb57bbf600ad7f70b008f45655605137eb20ecd3..5b219c244d63d11d7cbd187f48c0214495f2a5d0 100644 (file)
--- a/fs/unionfs/union.h
+++ b/fs/unionfs/union.h
@@ -230,7 +230,8 @@ extern int add_filldir_node(struct unionfs_dir_state *rdstate,
                            const char *name, int namelen, int bindex,
                            int whiteout);
 extern struct filldir_node *find_filldir_node(struct unionfs_dir_state *rdstate,
-                                             const char *name, int namelen);
+                                             const char *name, int namelen,
+                                             int is_whiteout);
 
 extern struct dentry **alloc_new_dentries(int objs);
 extern struct unionfs_data *alloc_new_data(int objs);