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Commit 7ada4db8 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

vfs: count unlinked inodes 



Add a new counter to the superblock that keeps track of unlinked but
not yet deleted inodes.

Do not WARN_ON if set_nlink is called with zero count, just do a
ratelimited printk.  This happens on xfs and probably other
filesystems after an unclean shutdown when the filesystem reads inodes
which already have zero i_nlink.  Reported by Christoph Hellwig.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Tested-by: default avatarToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 4ed5e82f

fs/inode.c

+85 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/ima.h>

#include <linux/cred.h>

#include <linux/buffer_head.h> /* for inode_has_buffers */

#include <linux/ratelimit.h>

#include "internal.h"



/*
@@ -242,6 +243,11 @@ void __destroy_inode(struct inode *inode) 
	BUG_ON(inode_has_buffers(inode));

	security_inode_free(inode);

	fsnotify_inode_delete(inode);

	if (!inode->i_nlink) {

		WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);

		atomic_long_dec(&inode->i_sb->s_remove_count);

	}



#ifdef CONFIG_FS_POSIX_ACL

	if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)

		posix_acl_release(inode->i_acl);
@@ -268,6 +274,85 @@ static void destroy_inode(struct inode *inode) 
		call_rcu(&inode->i_rcu, i_callback);

}



/**

 * drop_nlink - directly drop an inode's link count

 * @inode: inode

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.  In cases

 * where we are attempting to track writes to the

 * filesystem, a decrement to zero means an imminent

 * write when the file is truncated and actually unlinked

 * on the filesystem.

 */

void drop_nlink(struct inode *inode)

{

	WARN_ON(inode->i_nlink == 0);

	inode->__i_nlink--;

	if (!inode->i_nlink)

		atomic_long_inc(&inode->i_sb->s_remove_count);

}

EXPORT_SYMBOL(drop_nlink);



/**

 * clear_nlink - directly zero an inode's link count

 * @inode: inode

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.  See

 * drop_nlink() for why we care about i_nlink hitting zero.

 */

void clear_nlink(struct inode *inode)

{

	if (inode->i_nlink) {

		inode->__i_nlink = 0;

		atomic_long_inc(&inode->i_sb->s_remove_count);

	}

}

EXPORT_SYMBOL(clear_nlink);



/**

 * set_nlink - directly set an inode's link count

 * @inode: inode

 * @nlink: new nlink (should be non-zero)

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.

 */

void set_nlink(struct inode *inode, unsigned int nlink)

{

	if (!nlink) {

		printk_ratelimited(KERN_INFO

			"set_nlink() clearing i_nlink on %s inode %li\n",

			inode->i_sb->s_type->name, inode->i_ino);

		clear_nlink(inode);

	} else {

		/* Yes, some filesystems do change nlink from zero to one */

		if (inode->i_nlink == 0)

			atomic_long_dec(&inode->i_sb->s_remove_count);



		inode->__i_nlink = nlink;

	}

}

EXPORT_SYMBOL(set_nlink);



/**

 * inc_nlink - directly increment an inode's link count

 * @inode: inode

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.  Currently,

 * it is only here for parity with dec_nlink().

 */

void inc_nlink(struct inode *inode)

{

	if (WARN_ON(inode->i_nlink == 0))

		atomic_long_dec(&inode->i_sb->s_remove_count);



	inode->__i_nlink++;

}

EXPORT_SYMBOL(inc_nlink);



void address_space_init_once(struct address_space *mapping)

{

	memset(mapping, 0, sizeof(*mapping));

include/linux/fs.h

+7 −54
Original line number Diff line number Diff line
@@ -1483,6 +1483,9 @@ struct super_block { 


	struct shrinker s_shrink;	/* per-sb shrinker handle */



	/* Number of inodes with nlink == 0 but still referenced */

	atomic_long_t s_remove_count;



	/* Being remounted read-only */

	int s_readonly_remount;

};
@@ -1768,31 +1771,10 @@ static inline void mark_inode_dirty_sync(struct inode *inode) 
	__mark_inode_dirty(inode, I_DIRTY_SYNC);

}



/**

 * set_nlink - directly set an inode's link count

 * @inode: inode

 * @nlink: new nlink (should be non-zero)

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.

 */

static inline void set_nlink(struct inode *inode, unsigned int nlink)

{

	inode->__i_nlink = nlink;

}



/**

 * inc_nlink - directly increment an inode's link count

 * @inode: inode

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.  Currently,

 * it is only here for parity with dec_nlink().

 */

static inline void inc_nlink(struct inode *inode)

{

	inode->__i_nlink++;

}

extern void inc_nlink(struct inode *inode);

extern void drop_nlink(struct inode *inode);

extern void clear_nlink(struct inode *inode);

extern void set_nlink(struct inode *inode, unsigned int nlink);



static inline void inode_inc_link_count(struct inode *inode)

{
@@ -1800,35 +1782,6 @@ static inline void inode_inc_link_count(struct inode *inode) 
	mark_inode_dirty(inode);

}



/**

 * drop_nlink - directly drop an inode's link count

 * @inode: inode

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.  In cases

 * where we are attempting to track writes to the

 * filesystem, a decrement to zero means an imminent

 * write when the file is truncated and actually unlinked

 * on the filesystem.

 */

static inline void drop_nlink(struct inode *inode)

{

	inode->__i_nlink--;

}



/**

 * clear_nlink - directly zero an inode's link count

 * @inode: inode

 *

 * This is a low-level filesystem helper to replace any

 * direct filesystem manipulation of i_nlink.  See

 * drop_nlink() for why we care about i_nlink hitting zero.

 */

static inline void clear_nlink(struct inode *inode)

{

	inode->__i_nlink = 0;

}



static inline void inode_dec_link_count(struct inode *inode)

{

	drop_nlink(inode);