Commit 850d71ac authored by Al Viro's avatar Al Viro
Browse files

autofs: don't bother with atomics for ino->count 



All writers are serialized on inode->i_rwsem.  So are the readers
outside of expire.c.  And the readers in expire.c are in the
code that really doesn't care about narrow races - it's looking
for expiry candidates and its callers have to cope with the
possibility of a good candidate becoming busy right under them.

No point bothering with atomic operations - just use int and
mark the non-serialized readers with READ_ONCE().

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent c3aed166

fs/autofs/autofs_i.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -63,7 +63,7 @@ struct autofs_info { 




	struct autofs_sb_info *sbi;

	struct autofs_sb_info *sbi;

	unsigned long last_used;

	unsigned long last_used;

	atomic_t count;

	int count;





	kuid_t uid;

	kuid_t uid;

	kgid_t gid;

	kgid_t gid;

fs/autofs/expire.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -211,7 +211,7 @@ static int autofs_tree_busy(struct vfsmount *mnt, 
			}

			}

		} else {

		} else {

			struct autofs_info *ino = autofs_dentry_ino(p);

			struct autofs_info *ino = autofs_dentry_ino(p);

			unsigned int ino_count = atomic_read(&ino->count);

			unsigned int ino_count = READ_ONCE(ino->count);





			/* allow for dget above and top is already dgot */

			/* allow for dget above and top is already dgot */

			if (p == top)

			if (p == top)
@@ -379,7 +379,7 @@ static struct dentry *should_expire(struct dentry *dentry, 
		/* Not a forced expire? */

		/* Not a forced expire? */

		if (!(how & AUTOFS_EXP_FORCED)) {

		if (!(how & AUTOFS_EXP_FORCED)) {

			/* ref-walk currently on this dentry? */

			/* ref-walk currently on this dentry? */

			ino_count = atomic_read(&ino->count) + 1;

			ino_count = READ_ONCE(ino->count) + 1;

			if (d_count(dentry) > ino_count)

			if (d_count(dentry) > ino_count)

				return NULL;

				return NULL;

		}

		}
@@ -396,7 +396,7 @@ static struct dentry *should_expire(struct dentry *dentry, 
		/* Not a forced expire? */

		/* Not a forced expire? */

		if (!(how & AUTOFS_EXP_FORCED)) {

		if (!(how & AUTOFS_EXP_FORCED)) {

			/* ref-walk currently on this dentry? */

			/* ref-walk currently on this dentry? */

			ino_count = atomic_read(&ino->count) + 1;

			ino_count = READ_ONCE(ino->count) + 1;

			if (d_count(dentry) > ino_count)

			if (d_count(dentry) > ino_count)

				return NULL;

				return NULL;

		}

		}

fs/autofs/root.c

+10 −10
Original line number Original line Diff line number Diff line
@@ -569,9 +569,9 @@ static int autofs_dir_symlink(struct inode *dir, 
	d_add(dentry, inode);

	d_add(dentry, inode);





	dget(dentry);

	dget(dentry);

	atomic_inc(&ino->count);

	ino->count++;

	p_ino = autofs_dentry_ino(dentry->d_parent);

	p_ino = autofs_dentry_ino(dentry->d_parent);

	atomic_inc(&p_ino->count);

	p_ino->count++;





	dir->i_mtime = current_time(dir);

	dir->i_mtime = current_time(dir);
@@ -609,9 +609,9 @@ static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry) 
	if (sbi->flags & AUTOFS_SBI_CATATONIC)

	if (sbi->flags & AUTOFS_SBI_CATATONIC)

		return -EACCES;

		return -EACCES;





	atomic_dec(&ino->count);

	ino->count--;

	p_ino = autofs_dentry_ino(dentry->d_parent);

	p_ino = autofs_dentry_ino(dentry->d_parent);

	atomic_dec(&p_ino->count);

	p_ino->count--;

	dput(ino->dentry);

	dput(ino->dentry);





	d_inode(dentry)->i_size = 0;

	d_inode(dentry)->i_size = 0;
@@ -669,7 +669,7 @@ static void autofs_clear_leaf_automount_flags(struct dentry *dentry) 
	/* only consider parents below dentrys in the root */

	/* only consider parents below dentrys in the root */

	if (IS_ROOT(parent->d_parent))

	if (IS_ROOT(parent->d_parent))

		return;

		return;

	if (atomic_read(&autofs_dentry_ino(parent)->count) == 2)

	if (autofs_dentry_ino(parent)->count == 2)

		managed_dentry_set_managed(parent);

		managed_dentry_set_managed(parent);

}

}
@@ -691,7 +691,7 @@ static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry) 
	if (sbi->flags & AUTOFS_SBI_CATATONIC)

	if (sbi->flags & AUTOFS_SBI_CATATONIC)

		return -EACCES;

		return -EACCES;





	if (atomic_read(&ino->count) != 1)

	if (ino->count != 1)

		return -ENOTEMPTY;

		return -ENOTEMPTY;





	spin_lock(&sbi->lookup_lock);

	spin_lock(&sbi->lookup_lock);
@@ -702,9 +702,9 @@ static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry) 
	if (sbi->version < 5)

	if (sbi->version < 5)

		autofs_clear_leaf_automount_flags(dentry);

		autofs_clear_leaf_automount_flags(dentry);





	atomic_dec(&ino->count);

	ino->count--;

	p_ino = autofs_dentry_ino(dentry->d_parent);

	p_ino = autofs_dentry_ino(dentry->d_parent);

	atomic_dec(&p_ino->count);

	p_ino->count--;

	dput(ino->dentry);

	dput(ino->dentry);

	d_inode(dentry)->i_size = 0;

	d_inode(dentry)->i_size = 0;

	clear_nlink(d_inode(dentry));

	clear_nlink(d_inode(dentry));
@@ -750,9 +750,9 @@ static int autofs_dir_mkdir(struct inode *dir, 
		autofs_set_leaf_automount_flags(dentry);

		autofs_set_leaf_automount_flags(dentry);





	dget(dentry);

	dget(dentry);

	atomic_inc(&ino->count);

	ino->count++;

	p_ino = autofs_dentry_ino(dentry->d_parent);

	p_ino = autofs_dentry_ino(dentry->d_parent);

	atomic_inc(&p_ino->count);

	p_ino->count++;

	inc_nlink(dir);

	inc_nlink(dir);

	dir->i_mtime = current_time(dir);

	dir->i_mtime = current_time(dir);

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