diff options
| author | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 17:49:29 +1100 |
|---|---|---|
| committer | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 17:50:20 +1100 |
| commit | ec2447c278ee973d35f38e53ca16ba7f965ae33d (patch) | |
| tree | 5d17a0523c301b8c71c0f198ffe7782c5e9c0ea9 | |
| parent | b1e6a015a580ad145689ad1d6b4aa0e03e6c868b (diff) | |
| download | lwn-ec2447c278ee973d35f38e53ca16ba7f965ae33d.tar.gz lwn-ec2447c278ee973d35f38e53ca16ba7f965ae33d.zip | |
hostfs: simplify locking
Remove dcache_lock locking from hostfs filesystem, and move it into dcache
helpers. All that is required is a coherent path name. Protection from
concurrent modification of the namespace after path name generation is not
provided in current code, because dcache_lock is dropped before the path is
used.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
| -rw-r--r-- | fs/dcache.c | 15 | ||||
| -rw-r--r-- | fs/hostfs/hostfs_kern.c | 24 | ||||
| -rw-r--r-- | include/linux/dcache.h | 2 |
3 files changed, 24 insertions, 17 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 6f59f375ed9d..61beb40dd6bf 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2171,7 +2171,7 @@ 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; @@ -2198,7 +2198,18 @@ 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 cfe8bc7de511..39dc505ed273 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 1149e706f04d..cea27dfca532 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -311,7 +311,7 @@ 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.. */ |