Commit 6b255391 authored by Al Viro's avatar Al Viro
Browse files

replace ->follow_link() with new method that could stay in RCU mode 



new method: ->get_link(); replacement of ->follow_link().  The differences
are:
	* inode and dentry are passed separately
	* might be called both in RCU and non-RCU mode;
the former is indicated by passing it a NULL dentry.
	* when called that way it isn't allowed to block
and should return ERR_PTR(-ECHILD) if it needs to be called
in non-RCU mode.

It's a flagday change - the old method is gone, all in-tree instances
converted.  Conversion isn't hard; said that, so far very few instances
do not immediately bail out when called in RCU mode.  That'll change
in the next commits.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 21fc61c7

Documentation/filesystems/Locking

+2 −2
Original line number Diff line number Diff line
@@ -50,7 +50,7 @@ prototypes: 
	int (*rename2) (struct inode *, struct dentry *,

			struct inode *, struct dentry *, unsigned int);

	int (*readlink) (struct dentry *, char __user *,int);

	const char *(*follow_link) (struct dentry *, void **);

	const char *(*get_link) (struct dentry *, struct inode *, void **);

	void (*put_link) (struct inode *, void *);

	void (*truncate) (struct inode *);

	int (*permission) (struct inode *, int, unsigned int);
@@ -83,7 +83,7 @@ rmdir: yes (both) (see below) 
rename:		yes (all)	(see below)

rename2:	yes (all)	(see below)

readlink:	no

follow_link:	no

get_link:	no

put_link:	no

setattr:	yes

permission:	no (may not block if called in rcu-walk mode)

Documentation/filesystems/porting

+6 −0
Original line number Diff line number Diff line
@@ -509,3 +509,9 @@ in your dentry operations instead. 
	any symlink that might use page_follow_link_light/page_put_link() must

	have inode_nohighmem(inode) called before anything might start playing with

	its pagecache.

--

[mandatory]

	->follow_link() is replaced with ->get_link(); same API, except that

		* ->get_link() gets inode as a separate argument

		* ->get_link() may be called in RCU mode - in that case NULL

		  dentry is passed

drivers/staging/lustre/lustre/llite/symlink.c

+5 −3
Original line number Diff line number Diff line
@@ -118,12 +118,14 @@ failed: 
	return rc;

}



static const char *ll_follow_link(struct dentry *dentry, void **cookie)

static const char *ll_get_link(struct dentry *dentry,

			       struct inode *inode, void **cookie)

{

	struct inode *inode = d_inode(dentry);

	struct ptlrpc_request *request = NULL;

	int rc;

	char *symname = NULL;

	if (!dentry)

		return ERR_PTR(-ECHILD);



	CDEBUG(D_VFSTRACE, "VFS Op\n");

	ll_inode_size_lock(inode);
@@ -149,7 +151,7 @@ static void ll_put_link(struct inode *unused, void *cookie) 
struct inode_operations ll_fast_symlink_inode_operations = {

	.readlink	= generic_readlink,

	.setattr	= ll_setattr,

	.follow_link	= ll_follow_link,

	.get_link	= ll_get_link,

	.put_link	= ll_put_link,

	.getattr	= ll_getattr,

	.permission	= ll_inode_permission,

fs/9p/vfs_inode.c

+12 −5
Original line number Diff line number Diff line
@@ -1223,18 +1223,25 @@ ino_t v9fs_qid2ino(struct p9_qid *qid) 
}



/**

 * v9fs_vfs_follow_link - follow a symlink path

 * v9fs_vfs_get_link - follow a symlink path

 * @dentry: dentry for symlink

 * @inode: inode for symlink

 * @cookie: place to pass the data to put_link()

 */



static const char *v9fs_vfs_follow_link(struct dentry *dentry, void **cookie)

static const char *v9fs_vfs_get_link(struct dentry *dentry,

				     struct inode *inode, void **cookie)

{

	struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);

	struct p9_fid *fid = v9fs_fid_lookup(dentry);

	struct v9fs_session_info *v9ses;

	struct p9_fid *fid;

	struct p9_wstat *st;

	char *res;



	if (!dentry)

		return ERR_PTR(-ECHILD);



	v9ses = v9fs_dentry2v9ses(dentry);

	fid = v9fs_fid_lookup(dentry);

	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);



	if (IS_ERR(fid))
@@ -1452,7 +1459,7 @@ static const struct inode_operations v9fs_file_inode_operations = { 


static const struct inode_operations v9fs_symlink_inode_operations = {

	.readlink = generic_readlink,

	.follow_link = v9fs_vfs_follow_link,

	.get_link = v9fs_vfs_get_link,

	.put_link = kfree_put_link,

	.getattr = v9fs_vfs_getattr,

	.setattr = v9fs_vfs_setattr,

fs/9p/vfs_inode_dotl.c

+10 −4
Original line number Diff line number Diff line
@@ -899,20 +899,26 @@ error: 
}



/**

 * v9fs_vfs_follow_link_dotl - follow a symlink path

 * v9fs_vfs_get_link_dotl - follow a symlink path

 * @dentry: dentry for symlink

 * @inode: inode for symlink

 * @cookie: place to pass the data to put_link()

 */



static const char *

v9fs_vfs_follow_link_dotl(struct dentry *dentry, void **cookie)

v9fs_vfs_get_link_dotl(struct dentry *dentry,

		       struct inode *inode, void **cookie)

{

	struct p9_fid *fid = v9fs_fid_lookup(dentry);

	struct p9_fid *fid;

	char *target;

	int retval;



	if (!dentry)

		return ERR_PTR(-ECHILD);



	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);



	fid = v9fs_fid_lookup(dentry);

	if (IS_ERR(fid))

		return ERR_CAST(fid);

	retval = p9_client_readlink(fid, &target);
@@ -984,7 +990,7 @@ const struct inode_operations v9fs_file_inode_operations_dotl = { 


const struct inode_operations v9fs_symlink_inode_operations_dotl = {

	.readlink = generic_readlink,

	.follow_link = v9fs_vfs_follow_link_dotl,

	.get_link = v9fs_vfs_get_link_dotl,

	.put_link = kfree_put_link,

	.getattr = v9fs_vfs_getattr_dotl,

	.setattr = v9fs_vfs_setattr_dotl,

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