Unverified Commit 2f8f5a20 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!3888 fs/dcache.c: avoid panic while lockref of dentry overflow 

Merge Pull Request from: @ci-robot 
 
PR sync from: Zizhi Wo <wozizhi@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/XWDN4BOXGO576DIPI2Y75PLKVARWCPJF/ 
 
https://gitee.com/openeuler/kernel/issues/I8JDP6 
 
Link:https://gitee.com/openeuler/kernel/pulls/3888

 

Reviewed-by: default avatarzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parents 8aa69e79 cf619953

fs/dcache.c

+28 −4
Original line number Diff line number Diff line
@@ -1873,6 +1873,18 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) 
	return dentry;

}



static inline bool d_forbid_overflow(struct dentry *dentry)

{

	if (unlikely(d_count(dentry) >= D_COUNT_MAX)) {

		shrink_dcache_parent(dentry);



		if (d_count(dentry) >= D_COUNT_MAX)

			return false;

	}



	return true;

}



/**

 * d_alloc	-	allocate a dcache entry

 * @parent: parent of entry to allocate
@@ -1884,9 +1896,15 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) 
 */

struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)

{

	struct dentry *dentry = __d_alloc(parent->d_sb, name);

	struct dentry *dentry = NULL;



	if (unlikely(!d_forbid_overflow(parent)))

		goto out;



	dentry = __d_alloc(parent->d_sb, name);

	if (!dentry)

		return NULL;

		goto out;



	spin_lock(&parent->d_lock);

	/*

	 * don't need child lock because it is not subject
@@ -1896,7 +1914,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) 
	dentry->d_parent = parent;

	list_add(&dentry->d_child, &parent->d_subdirs);

	spin_unlock(&parent->d_lock);



out:

	return dentry;

}

EXPORT_SYMBOL(d_alloc);
@@ -1909,11 +1927,17 @@ EXPORT_SYMBOL(d_alloc_anon); 


struct dentry *d_alloc_cursor(struct dentry * parent)

{

	struct dentry *dentry = d_alloc_anon(parent->d_sb);

	struct dentry *dentry = NULL;



	if (unlikely(!d_forbid_overflow(parent)))

		goto out;



	dentry = d_alloc_anon(parent->d_sb);

	if (dentry) {

		dentry->d_flags |= DCACHE_DENTRY_CURSOR;

		dentry->d_parent = dget(parent);

	}

out:

	return dentry;

}

fs/filescontrol.c

+1 −1
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ 
#include <linux/sched/signal.h>

#include <linux/module.h>



#define FILES_MAX ULONG_MAX

#define FILES_MAX D_COUNT_MAX

#define FILES_MAX_STR "max"



static bool no_acct;

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -47,6 +47,9 @@ 
#include <asm/byteorder.h>

#include <uapi/linux/fs.h>



#define D_COUNT_MAX (INT_MAX / 2)





struct backing_dev_info;

struct bdi_writeback;

struct bio;