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Date: Sat, 27 Nov 2010 20:44:40 +1100
From: Nick Piggin <npiggin@...nel.dk>
To: linux-fsdevel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 10/46] hostfs: simplify locking
Remove dcache_lock locking from hostfs filesystem, and move it into dcache
helpers. All that should really be required is a coherent path name, protection
from concurrent modification is not provided outside path name generation
because dcache_lock is dropped before the path is used.
Signed-off-by: Nick Piggin <npiggin@...nel.dk>
---
fs/dcache.c | 15 +++++++++++++--
fs/hostfs/hostfs_kern.c | 24 ++++++++++--------------
include/linux/dcache.h | 2 +-
3 files changed, 24 insertions(+), 17 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 9fd5180..4f9ccbe 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2140,7 +2140,7 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
/*
* Write full pathname from the root of the filesystem into the buffer.
*/
-char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
+static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
{
char *end = buf + buflen;
char *retval;
@@ -2167,7 +2167,18 @@ char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Elong:
return ERR_PTR(-ENAMETOOLONG);
}
-EXPORT_SYMBOL(__dentry_path);
+
+char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
+{
+ char *retval;
+
+ spin_lock(&dcache_lock);
+ retval = __dentry_path(dentry, buf, buflen);
+ spin_unlock(&dcache_lock);
+
+ return retval;
+}
+EXPORT_SYMBOL(dentry_path_raw);
char *dentry_path(struct dentry *dentry, char *buf, int buflen)
{
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index cfe8bc7..39dc505 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -92,12 +92,10 @@ __uml_setup("hostfs=", hostfs_args,
static char *__dentry_name(struct dentry *dentry, char *name)
{
- char *p = __dentry_path(dentry, name, PATH_MAX);
+ char *p = dentry_path_raw(dentry, name, PATH_MAX);
char *root;
size_t len;
- spin_unlock(&dcache_lock);
-
root = dentry->d_sb->s_fs_info;
len = strlen(root);
if (IS_ERR(p)) {
@@ -123,25 +121,23 @@ static char *dentry_name(struct dentry *dentry)
if (!name)
return NULL;
- spin_lock(&dcache_lock);
return __dentry_name(dentry, name); /* will unlock */
}
static char *inode_name(struct inode *ino)
{
struct dentry *dentry;
- char *name = __getname();
- if (!name)
- return NULL;
+ char *name;
- spin_lock(&dcache_lock);
- if (list_empty(&ino->i_dentry)) {
- spin_unlock(&dcache_lock);
- __putname(name);
+ dentry = d_find_alias(ino);
+ if (!dentry)
return NULL;
- }
- dentry = list_first_entry(&ino->i_dentry, struct dentry, d_alias);
- return __dentry_name(dentry, name); /* will unlock */
+
+ name = dentry_name(dentry);
+
+ dput(dentry);
+
+ return name;
}
static char *follow_link(char *link)
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 4ef2af7..6b5760b 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -309,7 +309,7 @@ extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
extern char *__d_path(const struct path *path, struct path *root, char *, int);
extern char *d_path(const struct path *, char *, int);
extern char *d_path_with_unreachable(const struct path *, char *, int);
-extern char *__dentry_path(struct dentry *, char *, int);
+extern char *dentry_path_raw(struct dentry *, char *, int);
extern char *dentry_path(struct dentry *, char *, int);
/* Allocation counts.. */
--
1.7.1
--
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