ncpfs: get rid of d_validate() nonsense

What we want is to have non-counting references to children in
pagecache of parent directory, and avoid picking them after a child
has been freed.  Fine, so let's just have ->d_prune() clear
parent's inode "has directory contents in page cache" flag.
That way we don't need ->d_fsdata for storing offsets, so we can
use it as a quick and dirty "is it referenced from page cache"
flag.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 52 insertions, 77 deletions

diff --git a/fs/ncpfs/dir.c b/fs/ncpfs/dir.c
index 008960101520..e7ca827d7694 100644
--- a/fs/ncpfs/dir.c
+++ b/fs/ncpfs/dir.c
@@ -77,6 +77,7 @@ static int ncp_hash_dentry(const struct dentry *, struct qstr *);
 static int ncp_compare_dentry(const struct dentry *, const struct dentry *,
                 unsigned int, const char *, const struct qstr *);
 static int ncp_delete_dentry(const struct dentry *);
+static void ncp_d_prune(struct dentry *dentry);
 
 const struct dentry_operations ncp_dentry_operations =
 {
@@ -84,6 +85,7 @@ const struct dentry_operations ncp_dentry_operations =
         .d_hash         = ncp_hash_dentry,
         .d_compare      = ncp_compare_dentry,
         .d_delete       = ncp_delete_dentry,
+        .d_prune        = ncp_d_prune,
 };
 
 #define ncp_namespace(i)        (NCP_SERVER(i)->name_space[NCP_FINFO(i)->volNumber])
@@ -384,42 +386,6 @@ finished:
         return val;
 }
 
-static struct dentry *
-ncp_dget_fpos(struct dentry *dentry, struct dentry *parent, unsigned long fpos)
-{
-        struct dentry *dent = dentry;
-
-        if (d_validate(dent, parent)) {
-                if (dent->d_name.len <= NCP_MAXPATHLEN &&
-                    (unsigned long)dent->d_fsdata == fpos) {
-                        if (!dent->d_inode) {
-                                dput(dent);
-                                dent = NULL;
-                        }
-                        return dent;
-                }
-                dput(dent);
-        }
-
-        /* If a pointer is invalid, we search the dentry. */
-        spin_lock(&parent->d_lock);
-        list_for_each_entry(dent, &parent->d_subdirs, d_child) {
-                if ((unsigned long)dent->d_fsdata == fpos) {
-                        if (dent->d_inode)
-                                dget(dent);
-                        else
-                                dent = NULL;
-                        spin_unlock(&parent->d_lock);
-                        goto out;
-                }
-        }
-        spin_unlock(&parent->d_lock);
-        return NULL;
-
-out:
-        return dent;
-}
-
 static time_t ncp_obtain_mtime(struct dentry *dentry)
 {
         struct inode *inode = dentry->d_inode;
@@ -435,6 +401,20 @@ static time_t ncp_obtain_mtime(struct dentry *dentry)
         return ncp_date_dos2unix(i.modifyTime, i.modifyDate);
 }
 
+static inline void
+ncp_invalidate_dircache_entries(struct dentry *parent)
+{
+        struct ncp_server *server = NCP_SERVER(parent->d_inode);
+        struct dentry *dentry;
+
+        spin_lock(&parent->d_lock);
+        list_for_each_entry(dentry, &parent->d_subdirs, d_child) {
+                dentry->d_fsdata = NULL;
+                ncp_age_dentry(server, dentry);
+        }
+        spin_unlock(&parent->d_lock);
+}
+
 static int ncp_readdir(struct file *file, struct dir_context *ctx)
 {
         struct dentry *dentry = file->f_path.dentry;
@@ -500,10 +480,21 @@ static int ncp_readdir(struct file *file, struct dir_context *ctx)
                         struct dentry *dent;
                         bool over;
 
-                        dent = ncp_dget_fpos(ctl.cache->dentry[ctl.idx],
-                                                dentry, ctx->pos);
-                        if (!dent)
+                        spin_lock(&dentry->d_lock);
+                        if (!(NCP_FINFO(inode)->flags & NCPI_DIR_CACHE)) { 
+                                spin_unlock(&dentry->d_lock);
+                                goto invalid_cache;
+                        }
+                        dent = ctl.cache->dentry[ctl.idx];
+                        if (unlikely(!lockref_get_not_dead(&dent->d_lockref))) {
+                                spin_unlock(&dentry->d_lock);
+                                goto invalid_cache;
+                        }
+                        spin_unlock(&dentry->d_lock);
+                        if (!dent->d_inode) {
+                                dput(dent);
                                 goto invalid_cache;
+                        }
                         over = !dir_emit(ctx, dent->d_name.name,
                                         dent->d_name.len,
                                         dent->d_inode->i_ino, DT_UNKNOWN);
@@ -548,6 +539,9 @@ init_cache:
         ctl.filled = 0;
         ctl.valid  = 1;
 read_really:
+        spin_lock(&dentry->d_lock);
+        NCP_FINFO(inode)->flags |= NCPI_DIR_CACHE;
+        spin_unlock(&dentry->d_lock);
         if (ncp_is_server_root(inode)) {
                 ncp_read_volume_list(file, ctx, &ctl);
         } else {
@@ -573,6 +567,13 @@ out:
         return result;
 }
 
+static void ncp_d_prune(struct dentry *dentry)
+{
+        if (!dentry->d_fsdata)  /* not referenced from page cache */
+                return;
+        NCP_FINFO(dentry->d_parent->d_inode)->flags &= ~NCPI_DIR_CACHE;
+}
+
 static int
 ncp_fill_cache(struct file *file, struct dir_context *ctx,
                 struct ncp_cache_control *ctrl, struct ncp_entry_info *entry,
@@ -630,6 +631,10 @@ ncp_fill_cache(struct file *file, struct dir_context *ctx,
                         d_instantiate(newdent, inode);
                         if (!hashed)
                                 d_rehash(newdent);
+                } else {
+                        spin_lock(&dentry->d_lock);
+                        NCP_FINFO(inode)->flags &= ~NCPI_DIR_CACHE;
+                        spin_unlock(&dentry->d_lock);
                 }
         } else {
                 struct inode *inode = newdent->d_inode;
@@ -639,12 +644,6 @@ ncp_fill_cache(struct file *file, struct dir_context *ctx,
                 mutex_unlock(&inode->i_mutex);
         }
 
-        if (newdent->d_inode) {
-                ino = newdent->d_inode->i_ino;
-                newdent->d_fsdata = (void *) ctl.fpos;
-                ncp_new_dentry(newdent);
-        }
-
         if (ctl.idx >= NCP_DIRCACHE_SIZE) {
                 if (ctl.page) {
                         kunmap(ctl.page);
@@ -660,8 +659,13 @@ ncp_fill_cache(struct file *file, struct dir_context *ctx,
                         ctl.cache = kmap(ctl.page);
         }
         if (ctl.cache) {
-                ctl.cache->dentry[ctl.idx] = newdent;
-                valid = 1;
+                if (newdent->d_inode) {
+                        newdent->d_fsdata = newdent;
+                        ctl.cache->dentry[ctl.idx] = newdent;
+                        ino = newdent->d_inode->i_ino;
+                        ncp_new_dentry(newdent);
+                }
+                valid = 1;
         }
         dput(newdent);
 end_advance:
diff --git a/fs/ncpfs/ncp_fs_i.h b/fs/ncpfs/ncp_fs_i.h
index 4b0bec477846..c4794504f843 100644
--- a/fs/ncpfs/ncp_fs_i.h
+++ b/fs/ncpfs/ncp_fs_i.h
@@ -22,6 +22,7 @@ struct ncp_inode_info {
         int     access;
         int     flags;
 #define NCPI_KLUDGE_SYMLINK     0x0001
+#define NCPI_DIR_CACHE          0x0002
         __u8    file_handle[6];
         struct inode vfs_inode;
 };
diff --git a/fs/ncpfs/ncplib_kernel.h b/fs/ncpfs/ncplib_kernel.h
index b785f74bfe3c..250e443a07f3 100644
--- a/fs/ncpfs/ncplib_kernel.h
+++ b/fs/ncpfs/ncplib_kernel.h
@@ -184,36 +184,6 @@ ncp_new_dentry(struct dentry* dentry)
         dentry->d_time = jiffies;
 }
 
-static inline void
-ncp_renew_dentries(struct dentry *parent)
-{
-        struct ncp_server *server = NCP_SERVER(parent->d_inode);
-        struct dentry *dentry;
-
-        spin_lock(&parent->d_lock);
-        list_for_each_entry(dentry, &parent->d_subdirs, d_child) {
-                if (dentry->d_fsdata == NULL)
-                        ncp_age_dentry(server, dentry);
-                else
-                        ncp_new_dentry(dentry);
-        }
-        spin_unlock(&parent->d_lock);
-}
-
-static inline void
-ncp_invalidate_dircache_entries(struct dentry *parent)
-{
-        struct ncp_server *server = NCP_SERVER(parent->d_inode);
-        struct dentry *dentry;
-
-        spin_lock(&parent->d_lock);
-        list_for_each_entry(dentry, &parent->d_subdirs, d_child) {
-                dentry->d_fsdata = NULL;
-                ncp_age_dentry(server, dentry);
-        }
-        spin_unlock(&parent->d_lock);
-}
-
 struct ncp_cache_head {
         time_t          mtime;
         unsigned long   time;   /* cache age */