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Commit 41edf278 authored by Al Viro's avatar Al Viro
Browse files

dentry_kill(): don't try to remove from shrink list 



If the victim in on the shrink list, don't remove it from there.
If shrink_dentry_list() manages to remove it from the list before
we are done - fine, we'll just free it as usual.  If not - mark
it with new flag (DCACHE_MAY_FREE) and leave it there.

Eventually, shrink_dentry_list() will get to it, remove the sucker
from shrink list and call dentry_kill(dentry, 0).  Which is where
we'll deal with freeing.

Since now dentry_kill(dentry, 0) may happen after or during
dentry_kill(dentry, 1), we need to recognize that (by seeing
DCACHE_DENTRY_KILLED already set), unlock everything
and either free the sucker (in case DCACHE_MAY_FREE has been
set) or leave it for ongoing dentry_kill(dentry, 1) to deal with.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 01b60351

fs/dcache.c

+19 −8
Original line number Diff line number Diff line
@@ -468,7 +468,14 @@ dentry_kill(struct dentry *dentry, int unlock_on_failure) 
	__releases(dentry->d_lock)

{

	struct inode *inode;

	struct dentry *parent;

	struct dentry *parent = NULL;

	bool can_free = true;



	if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {

		can_free = dentry->d_flags & DCACHE_MAY_FREE;

		spin_unlock(&dentry->d_lock);

		goto out;

	}



	inode = dentry->d_inode;

	if (inode && !spin_trylock(&inode->i_lock)) {
@@ -479,9 +486,7 @@ dentry_kill(struct dentry *dentry, int unlock_on_failure) 
		}

		return dentry; /* try again with same dentry */

	}

	if (IS_ROOT(dentry))

		parent = NULL;

	else

	if (!IS_ROOT(dentry))

		parent = dentry->d_parent;

	if (parent && !spin_trylock(&parent->d_lock)) {

		if (inode)
@@ -504,8 +509,6 @@ dentry_kill(struct dentry *dentry, int unlock_on_failure) 
	if (dentry->d_flags & DCACHE_LRU_LIST) {

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

			d_lru_del(dentry);

		else

			d_shrink_del(dentry);

	}

	/* if it was on the hash then remove it */

	__d_drop(dentry);
@@ -527,6 +530,14 @@ dentry_kill(struct dentry *dentry, int unlock_on_failure) 
	if (dentry->d_op && dentry->d_op->d_release)

		dentry->d_op->d_release(dentry);



	spin_lock(&dentry->d_lock);

	if (dentry->d_flags & DCACHE_SHRINK_LIST) {

		dentry->d_flags |= DCACHE_MAY_FREE;

		can_free = false;

	}

	spin_unlock(&dentry->d_lock);

out:

	if (likely(can_free))

		dentry_free(dentry);

	return parent;

}
@@ -829,7 +840,7 @@ static void shrink_dentry_list(struct list_head *list) 
		 * We found an inuse dentry which was not removed from

		 * the LRU because of laziness during lookup. Do not free it.

		 */

		if (dentry->d_lockref.count) {

		if ((int)dentry->d_lockref.count > 0) {

			spin_unlock(&dentry->d_lock);

			continue;

		}

include/linux/dcache.h

+2 −0
Original line number Diff line number Diff line
@@ -221,6 +221,8 @@ struct dentry_operations { 
#define DCACHE_SYMLINK_TYPE		0x00300000 /* Symlink */

#define DCACHE_FILE_TYPE		0x00400000 /* Other file type */



#define DCACHE_MAY_FREE			0x00800000



extern seqlock_t rename_lock;



static inline int dname_external(const struct dentry *dentry)