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Commit ec2447c2 authored by Nick Piggin's avatar Nick Piggin
Browse files

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: default avatarNick Piggin <npiggin@kernel.dk>
parent b1e6a015

fs/dcache.c

+13 −2
Original line number Original line Diff line number Diff line
@@ -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.

 * 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 *end = buf + buflen;

	char *retval;

	char *retval;
@@ -2198,7 +2198,18 @@ char *__dentry_path(struct dentry *dentry, char *buf, int buflen) 
Elong:

Elong:

	return ERR_PTR(-ENAMETOOLONG);

	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)

char *dentry_path(struct dentry *dentry, char *buf, int buflen)

{

{

fs/hostfs/hostfs_kern.c

+10 −14
Original line number Original line Diff line number Diff line
@@ -92,12 +92,10 @@ __uml_setup("hostfs=", hostfs_args, 




static char *__dentry_name(struct dentry *dentry, char *name)

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;

	char *root;

	size_t len;

	size_t len;





	spin_unlock(&dcache_lock);



	root = dentry->d_sb->s_fs_info;

	root = dentry->d_sb->s_fs_info;

	len = strlen(root);

	len = strlen(root);

	if (IS_ERR(p)) {

	if (IS_ERR(p)) {
@@ -123,25 +121,23 @@ static char *dentry_name(struct dentry *dentry) 
	if (!name)

	if (!name)

		return NULL;

		return NULL;





	spin_lock(&dcache_lock);

	return __dentry_name(dentry, name); /* will unlock */

	return __dentry_name(dentry, name); /* will unlock */

}

}





static char *inode_name(struct inode *ino)

static char *inode_name(struct inode *ino)

{

{

	struct dentry *dentry;

	struct dentry *dentry;

	char *name = __getname();

	char *name;

	if (!name)

		return NULL;





	spin_lock(&dcache_lock);

	dentry = d_find_alias(ino);

	if (list_empty(&ino->i_dentry)) {

	if (!dentry)

		spin_unlock(&dcache_lock);

		__putname(name);

		return NULL;

		return NULL;

	}



	dentry = list_first_entry(&ino->i_dentry, struct dentry, d_alias);

	name = dentry_name(dentry);

	return __dentry_name(dentry, name); /* will unlock */



	dput(dentry);



	return name;

}

}





static char *follow_link(char *link)

static char *follow_link(char *link)

include/linux/dcache.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -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 *path, struct path *root, char *, int);

extern char *d_path(const struct path *, char *, int);

extern char *d_path(const struct path *, char *, int);

extern char *d_path_with_unreachable(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);

extern char *dentry_path(struct dentry *, char *, int);





/* Allocation counts.. */

/* Allocation counts.. */