[patch 1/3] vfs: dcache cleanups

[Miklos Szeredi]

From: Miklos Szeredi <mszeredi@xxxxxxx>

d_path() cleanups and fix the following sparse warnings:

fs/dcache.c:2183:19: warning: symbol 'filp_cachep' was not declared. Should it be static?
fs/dcache.c:115:3: warning: context imbalance in 'dentry_iput' - unexpected unlock
fs/dcache.c:188:2: warning: context imbalance in 'dput' - different lock contexts for basic block
fs/dcache.c:400:2: warning: context imbalance in 'prune_one_dentry' - different lock contexts for basic block
fs/dcache.c:431:22: warning: context imbalance in 'prune_dcache' - different lock contexts for basic block
fs/dcache.c:563:2: warning: context imbalance in 'shrink_dcache_sb' - different lock contexts for basic block
fs/dcache.c:1385:6: warning: context imbalance in 'd_delete' - wrong count at exit
fs/dcache.c:1636:2: warning: context imbalance in '__d_unalias' - unexpected unlock
fs/dcache.c:1735:2: warning: context imbalance in 'd_materialise_unique' - different lock contexts for basic block

Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Acked-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
---
 fs/dcache.c |   51 +++++++++++++++++++++++++--------------------------
 1 file changed, 25 insertions(+), 26 deletions(-)

Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c	2008-06-11 10:16:10.000000000 +0200
+++ linux-2.6/fs/dcache.c	2008-06-13 13:12:57.000000000 +0200
@@ -17,6 +17,7 @@
 #include <linux/syscalls.h>
 #include <linux/string.h>
 #include <linux/mm.h>
+#include <linux/fdtable.h>
 #include <linux/fs.h>
 #include <linux/fsnotify.h>
 #include <linux/slab.h>
@@ -106,9 +107,10 @@ static void dentry_lru_remove(struct den
 /*
  * Release the dentry's inode, using the filesystem
  * d_iput() operation if defined.
- * Called with dcache_lock and per dentry lock held, drops both.
  */
 static void dentry_iput(struct dentry * dentry)
+	__releases(dentry->d_lock)
+	__releases(dcache_lock)
 {
 	struct inode *inode = dentry->d_inode;
 	if (inode) {
@@ -132,12 +134,13 @@ static void dentry_iput(struct dentry * 
  * d_kill - kill dentry and return parent
  * @dentry: dentry to kill
  *
- * Called with dcache_lock and d_lock, releases both.  The dentry must
- * already be unhashed and removed from the LRU.
+ * The dentry must already be unhashed and removed from the LRU.
  *
  * If this is the root of the dentry tree, return NULL.
  */
 static struct dentry *d_kill(struct dentry *dentry)
+	__releases(dentry->d_lock)
+	__releases(dcache_lock)
 {
 	struct dentry *parent;
 
@@ -383,11 +386,11 @@ restart:
  * Try to prune ancestors as well.  This is necessary to prevent
  * quadratic behavior of shrink_dcache_parent(), but is also expected
  * to be beneficial in reducing dentry cache fragmentation.
- *
- * Called with dcache_lock, drops it and then regains.
- * Called with dentry->d_lock held, drops it.
  */
 static void prune_one_dentry(struct dentry * dentry)
+	__releases(dentry->d_lock)
+	__releases(dcache_lock)
+	__acquires(dcache_lock)
 {
 	__d_drop(dentry);
 	dentry = d_kill(dentry);
@@ -1604,10 +1607,9 @@ static int d_isparent(struct dentry *p1,
  *
  * Note: If ever the locking in lock_rename() changes, then please
  * remember to update this too...
- *
- * On return, dcache_lock will have been unlocked.
  */
 static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
+	__releases(dcache_lock)
 {
 	struct mutex *m1 = NULL, *m2 = NULL;
 	struct dentry *ret;
@@ -1743,7 +1745,6 @@ out_nolock:
 shouldnt_be_hashed:
 	spin_unlock(&dcache_lock);
 	BUG();
-	goto shouldnt_be_hashed;
 }
 
 static int prepend(char **buffer, int *buflen, const char *str,
@@ -1758,7 +1759,7 @@ static int prepend(char **buffer, int *b
 }
 
 /**
- * d_path - return the path of a dentry
+ * __d_path - return the path of a dentry
  * @path: the dentry/vfsmount to report
  * @root: root vfsmnt/dentry (may be modified by this function)
  * @buffer: buffer to return value in
@@ -1779,8 +1780,9 @@ char *__d_path(const struct path *path, 
 {
 	struct dentry *dentry = path->dentry;
 	struct vfsmount *vfsmnt = path->mnt;
-	char * end = buffer+buflen;
-	char * retval;
+	char *end = buffer + buflen;
+	char *retval;
+	struct qstr *name;
 
 	prepend(&end, &buflen, "\0", 1);
 	if (!IS_ROOT(dentry) && d_unhashed(dentry) &&
@@ -1812,8 +1814,8 @@ char *__d_path(const struct path *path, 
 		}
 		parent = dentry->d_parent;
 		prefetch(parent);
-		if ((prepend(&end, &buflen, dentry->d_name.name,
-				dentry->d_name.len) != 0) ||
+		name = &dentry->d_name;
+		if ((prepend(&end, &buflen, name->name, name->len) != 0) ||
 		    (prepend(&end, &buflen, "/", 1) != 0))
 			goto Elong;
 		retval = end;
@@ -1824,8 +1826,8 @@ char *__d_path(const struct path *path, 
 
 global_root:
 	retval += 1;	/* hit the slash */
-	if (prepend(&retval, &buflen, dentry->d_name.name,
-		    dentry->d_name.len) != 0)
+	name = &dentry->d_name;
+	if (prepend(&retval, &buflen, name->name, name->len) != 0)
 		goto Elong;
 	root->mnt = vfsmnt;
 	root->dentry = dentry;
@@ -1845,7 +1847,7 @@ Elong:
  *
  * Returns the buffer or an error code if the path was too long.
  *
- * "buflen" should be positive. Caller holds the dcache_lock.
+ * "buflen" should be positive.
  */
 char *d_path(struct path *path, char *buf, int buflen)
 {
@@ -1915,16 +1917,13 @@ char *dentry_path(struct dentry *dentry,
 	retval = end-1;
 	*retval = '/';
 
-	for (;;) {
-		struct dentry *parent;
-		if (IS_ROOT(dentry))
-			break;
+	while (!IS_ROOT(dentry)) {
+		struct dentry *parent = dentry->d_parent;
+		struct qstr *name;
 
-		parent = dentry->d_parent;
 		prefetch(parent);
-
-		if ((prepend(&end, &buflen, dentry->d_name.name,
-				dentry->d_name.len) != 0) ||
+		name = &dentry->d_name;
+		if ((prepend(&end, &buflen, name->name, name->len) != 0) ||
 		    (prepend(&end, &buflen, "/", 1) != 0))
 			goto Elong;
 
@@ -1975,7 +1974,7 @@ asmlinkage long sys_getcwd(char __user *
 	error = -ENOENT;
 	/* Has the current directory has been unlinked? */
 	spin_lock(&dcache_lock);
-	if (pwd.dentry->d_parent == pwd.dentry || !d_unhashed(pwd.dentry)) {
+	if (IS_ROOT(pwd.dentry) || !d_unhashed(pwd.dentry)) {
 		unsigned long len;
 		struct path tmp = root;
 		char * cwd;

--
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