Commit b5b80177 authored by Ian Kent's avatar Ian Kent Committed by Al Viro
Browse files

autofs4: Add d_manage() dentry operation 



This patch required a previous patch to add the ->d_automount()
dentry operation.

Add a function to use the newly defined ->d_manage() dentry operation
for blocking during mount and expire.

Whether the VFS calls the dentry operations d_automount() and d_manage()
is controled by the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags. autofs
uses the d_automount() operation to callback to user space to request
mount operations and the d_manage() operation to block walks into mounts
that are under construction or destruction.

In order to prevent these functions from being called unnecessarily the
DMANAGED_* flags are cleared for cases which would cause this. In the
common case the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags are both
set for dentrys waiting to be mounted. The DMANAGED_TRANSIT flag is
cleared upon successful mount request completion and set during expire
runs, both during the dentry expire check, and if selected for expire,
is left set until a subsequent successful mount request completes.

The exception to this is the so-called rootless multi-mount which has
no actual mount at its base. In this case the DMANAGED_AUTOMOUNT flag
is cleared upon successful mount request completion as well and set
again after a successful expire.

Signed-off-by: default avatarIan Kent <raven@themaw.net>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 10584211

fs/autofs4/autofs_i.h

+49 −1
Original line number Diff line number Diff line
@@ -99,7 +99,6 @@ struct autofs_info { 
};



#define AUTOFS_INF_EXPIRING	(1<<0) /* dentry is in the process of expiring */

#define AUTOFS_INF_MOUNTPOINT	(1<<1) /* mountpoint status for direct expire */

#define AUTOFS_INF_PENDING	(1<<2) /* dentry pending mount */



struct autofs_wait_queue {
@@ -221,6 +220,7 @@ extern const struct file_operations autofs4_root_operations; 
/* Operations methods */



struct vfsmount *autofs4_d_automount(struct path *);

int autofs4_d_manage(struct dentry *, bool);



/* VFS automount flags management functions */
@@ -248,6 +248,54 @@ static inline void managed_dentry_clear_automount(struct dentry *dentry) 
	spin_unlock(&dentry->d_lock);

}



static inline void __managed_dentry_set_transit(struct dentry *dentry)

{

	dentry->d_flags |= DCACHE_MANAGE_TRANSIT;

}



static inline void managed_dentry_set_transit(struct dentry *dentry)

{

	spin_lock(&dentry->d_lock);

	__managed_dentry_set_transit(dentry);

	spin_unlock(&dentry->d_lock);

}



static inline void __managed_dentry_clear_transit(struct dentry *dentry)

{

	dentry->d_flags &= ~DCACHE_MANAGE_TRANSIT;

}



static inline void managed_dentry_clear_transit(struct dentry *dentry)

{

	spin_lock(&dentry->d_lock);

	__managed_dentry_clear_transit(dentry);

	spin_unlock(&dentry->d_lock);

}



static inline void __managed_dentry_set_managed(struct dentry *dentry)

{

	dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);

}



static inline void managed_dentry_set_managed(struct dentry *dentry)

{

	spin_lock(&dentry->d_lock);

	__managed_dentry_set_managed(dentry);

	spin_unlock(&dentry->d_lock);

}



static inline void __managed_dentry_clear_managed(struct dentry *dentry)

{

	dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);

}



static inline void managed_dentry_clear_managed(struct dentry *dentry)

{

	spin_lock(&dentry->d_lock);

	__managed_dentry_clear_managed(dentry);

	spin_unlock(&dentry->d_lock);

}



/* Initializing function */



int autofs4_fill_super(struct super_block *, void *, int);

fs/autofs4/expire.c

+26 −25
Original line number Diff line number Diff line
@@ -26,10 +26,6 @@ static inline int autofs4_can_expire(struct dentry *dentry, 
	if (ino == NULL)

		return 0;



	/* No point expiring a pending mount */

	if (ino->flags & AUTOFS_INF_PENDING)

		return 0;



	if (!do_now) {

		/* Too young to die */

		if (!timeout || time_after(ino->last_used + timeout, now))
@@ -283,6 +279,7 @@ struct dentry *autofs4_expire_direct(struct super_block *sb, 
	unsigned long timeout;

	struct dentry *root = dget(sb->s_root);

	int do_now = how & AUTOFS_EXP_IMMEDIATE;

	struct autofs_info *ino;



	if (!root)

		return NULL;
@@ -291,20 +288,21 @@ struct dentry *autofs4_expire_direct(struct super_block *sb, 
	timeout = sbi->exp_timeout;



	spin_lock(&sbi->fs_lock);

	ino = autofs4_dentry_ino(root);

	/* No point expiring a pending mount */

	if (ino->flags & AUTOFS_INF_PENDING) {

		spin_unlock(&sbi->fs_lock);

		return NULL;

	}

	managed_dentry_set_transit(root);

	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {

		struct autofs_info *ino = autofs4_dentry_ino(root);

		if (d_mountpoint(root)) {

			ino->flags |= AUTOFS_INF_MOUNTPOINT;

			spin_lock(&root->d_lock);

			root->d_flags &= ~DCACHE_MOUNTED;

			spin_unlock(&root->d_lock);

		}

		ino->flags |= AUTOFS_INF_EXPIRING;

		managed_dentry_set_automount(root);

		init_completion(&ino->expire_complete);

		spin_unlock(&sbi->fs_lock);

		return root;

	}

	managed_dentry_clear_transit(root);

	spin_unlock(&sbi->fs_lock);

	dput(root);
@@ -341,6 +339,10 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, 
	while ((dentry = get_next_positive_dentry(dentry, root))) {

		spin_lock(&sbi->fs_lock);

		ino = autofs4_dentry_ino(dentry);

		/* No point expiring a pending mount */

		if (ino->flags & AUTOFS_INF_PENDING)

			goto cont;

		managed_dentry_set_transit(dentry);



		/*

		 * Case 1: (i) indirect mount or top level pseudo direct mount
@@ -400,6 +402,8 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, 
			}

		}

next:

		managed_dentry_clear_transit(dentry);

cont:

		spin_unlock(&sbi->fs_lock);

	}

	return NULL;
@@ -409,7 +413,6 @@ found: 
		expired, (int)expired->d_name.len, expired->d_name.name);

	ino = autofs4_dentry_ino(expired);

	ino->flags |= AUTOFS_INF_EXPIRING;

	managed_dentry_set_automount(expired);

	init_completion(&ino->expire_complete);

	spin_unlock(&sbi->fs_lock);

	spin_lock(&autofs4_lock);
@@ -482,7 +485,7 @@ int autofs4_expire_run(struct super_block *sb, 
	ino = autofs4_dentry_ino(dentry);

	ino->flags &= ~AUTOFS_INF_EXPIRING;

	if (!d_unhashed(dentry))

		managed_dentry_clear_automount(dentry);

		managed_dentry_clear_transit(dentry);

	complete_all(&ino->expire_complete);

	spin_unlock(&sbi->fs_lock);
@@ -508,20 +511,18 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, 
		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);



		spin_lock(&sbi->fs_lock);

		if (ino->flags & AUTOFS_INF_MOUNTPOINT) {

			spin_lock(&sb->s_root->d_lock);

			/*

			 * If we haven't been expired away, then reset

			 * mounted status.

			 */

			if (mnt->mnt_parent != mnt)

				sb->s_root->d_flags |= DCACHE_MOUNTED;

			spin_unlock(&sb->s_root->d_lock);

			ino->flags &= ~AUTOFS_INF_MOUNTPOINT;

		}

		ino->flags &= ~AUTOFS_INF_EXPIRING;

		spin_lock(&dentry->d_lock);

		if (ret)

			managed_dentry_clear_automount(dentry);

			__managed_dentry_clear_transit(dentry);

		else {

			if ((IS_ROOT(dentry) ||

			    (autofs_type_indirect(sbi->type) &&

			     IS_ROOT(dentry->d_parent))) &&

			    !(dentry->d_flags & DCACHE_NEED_AUTOMOUNT))

				__managed_dentry_set_automount(dentry);

		}

		spin_unlock(&dentry->d_lock);

		complete_all(&ino->expire_complete);

		spin_unlock(&sbi->fs_lock);

		dput(dentry);

fs/autofs4/inode.c

+2 −1
Original line number Diff line number Diff line
@@ -253,6 +253,7 @@ static struct autofs_info *autofs4_mkroot(struct autofs_sb_info *sbi) 


static const struct dentry_operations autofs4_sb_dentry_operations = {

	.d_automount	= autofs4_d_automount,

	.d_manage	= autofs4_d_manage,

	.d_release      = autofs4_dentry_release,

};
@@ -322,7 +323,7 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent) 
	}



	if (autofs_type_trigger(sbi->type))

		__managed_dentry_set_automount(root);

		__managed_dentry_set_managed(root);



	root_inode->i_fop = &autofs4_root_operations;

	root_inode->i_op = autofs_type_trigger(sbi->type) ?

fs/autofs4/root.c

+82 −13
Original line number Diff line number Diff line
@@ -424,6 +424,7 @@ static const struct dentry_operations autofs4_root_dentry_operations = { 
/* For other dentries */

static const struct dentry_operations autofs4_dentry_operations = {

	.d_automount	= autofs4_d_automount,

	.d_manage	= autofs4_d_manage,

	.d_release	= autofs4_dentry_release,

};
@@ -604,6 +605,18 @@ struct vfsmount *autofs4_d_automount(struct path *path) 
	DPRINTK("dentry=%p %.*s",

		dentry, dentry->d_name.len, dentry->d_name.name);



	/*

	 * Someone may have manually umounted this or it was a submount

	 * that has gone away.

	 */

	spin_lock(&dentry->d_lock);

	if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {

		if (!(dentry->d_flags & DCACHE_MANAGE_TRANSIT) &&

		     (dentry->d_flags & DCACHE_NEED_AUTOMOUNT))

			__managed_dentry_set_transit(path->dentry);

	}

	spin_unlock(&dentry->d_lock);



	/* The daemon never triggers a mount. */

	if (autofs4_oz_mode(sbi))

		return NULL;
@@ -633,31 +646,63 @@ struct vfsmount *autofs4_d_automount(struct path *path) 


	/*

	 * If the dentry is a symlink it's equivalent to a directory

	 * having d_mounted() true, so there's no need to call back

	 * having d_mountpoint() true, so there's no need to call back

	 * to the daemon.

	 */

	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode))

		goto done;

	if (!d_mountpoint(dentry)) {

		/*

		 * It's possible that user space hasn't removed directories

		 * after umounting a rootless multi-mount, although it

		 * should. For v5 have_submounts() is sufficient to handle

		 * this because the leaves of the directory tree under the

		 * mount never trigger mounts themselves (they have an autofs

		 * trigger mount mounted on them). But v4 pseudo direct mounts

		 * do need the leaves to to trigger mounts. In this case we

		 * have no choice but to use the list_empty() check and

		 * require user space behave.

		 */

		if (sbi->version > 4) {

			if (have_submounts(dentry))

				goto done;

		} else {

			spin_lock(&dentry->d_lock);

	if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {

		ino->flags |= AUTOFS_INF_PENDING;

			if (!list_empty(&dentry->d_subdirs)) {

				spin_unlock(&dentry->d_lock);

				goto done;

			}

			spin_unlock(&dentry->d_lock);

		}

		ino->flags |= AUTOFS_INF_PENDING;

		spin_unlock(&sbi->fs_lock);

		status = autofs4_mount_wait(dentry);

		if (status)

			return ERR_PTR(status);

		spin_lock(&sbi->fs_lock);

		ino->flags &= ~AUTOFS_INF_PENDING;

		goto done;

	}

	spin_unlock(&dentry->d_lock);

done:

	if (!(ino->flags & AUTOFS_INF_EXPIRING)) {

		/*

		 * Any needed mounting has been completed and the path updated

		 * so turn this into a normal dentry so we don't continually

	 * call ->d_automount().

		 * call ->d_automount() and ->d_manage().

		 */

	managed_dentry_clear_automount(dentry);

		spin_lock(&dentry->d_lock);

		__managed_dentry_clear_transit(dentry);

		/*

		 * Only clear DMANAGED_AUTOMOUNT for rootless multi-mounts and

		 * symlinks as in all other cases the dentry will be covered by

		 * an actual mount so ->d_automount() won't be called during

		 * the follow.

		 */

		if ((!d_mountpoint(dentry) &&

		    !list_empty(&dentry->d_subdirs)) ||

		    (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)))

			__managed_dentry_clear_automount(dentry);

		spin_unlock(&dentry->d_lock);

	}

	spin_unlock(&sbi->fs_lock);



	/* Mount succeeded, check if we ended up with a new dentry */
@@ -668,6 +713,30 @@ done: 
	return NULL;

}



int autofs4_d_manage(struct dentry *dentry, bool mounting_here)

{

	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);



	DPRINTK("dentry=%p %.*s",

		dentry, dentry->d_name.len, dentry->d_name.name);



	/* The daemon never waits. */

	if (autofs4_oz_mode(sbi) || mounting_here) {

		if (!d_mountpoint(dentry))

			return -EISDIR;

		return 0;

	}



	/* Wait for pending expires */

	do_expire_wait(dentry);



	/*

	 * This dentry may be under construction so wait on mount

	 * completion.

	 */

	return autofs4_mount_wait(dentry);

}



/* Lookups in the root directory */

static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)

{
@@ -704,7 +773,7 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s 
		/* Mark entries in the root as mount triggers */

		if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent)) {

			d_set_d_op(dentry, &autofs4_dentry_operations);

			managed_dentry_set_automount(dentry);

			__managed_dentry_set_managed(dentry);

		}



		ino = autofs4_init_ino(NULL, sbi, 0555);

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