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Revision 38d78e587d4960d0db94add518d27ee74bad2301 authored by Vladimir Davydov on 22 March 2013, 22:04:51 UTC, committed by Linus Torvalds on 22 March 2013, 23:41:21 UTC 
mqueue: sys_mq_open: do not call mnt_drop_write() if read-only
 
mnt_drop_write() must be called only if mnt_want_write() succeeded,
otherwise the mnt_writers counter will diverge.

mnt_writers counters are used to check if remounting FS as read-only is
OK, so after an extra mnt_drop_write() call, it would be impossible to
remount mqueue FS as read-only.  Besides, on umount a warning would be
printed like this one:

  =====================================
  [ BUG: bad unlock balance detected! ]
  3.9.0-rc3 #5 Not tainted
  -------------------------------------
  a.out/12486 is trying to release lock (sb_writers) at:
  mnt_drop_write+0x1f/0x30
  but there are no more locks to release!

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent ca4b3f3
Raw File
dentry.c 
/*
 *  linux/fs/hpfs/dentry.c
 *
 *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
 *
 *  dcache operations
 */

#include "hpfs_fn.h"

/*
 * Note: the dentry argument is the parent dentry.
 */

static int hpfs_hash_dentry(const struct dentry *dentry, const struct inode *inode,
		struct qstr *qstr)
{
	unsigned long	 hash;
	int		 i;
	unsigned l = qstr->len;

	if (l == 1) if (qstr->name[0]=='.') goto x;
	if (l == 2) if (qstr->name[0]=='.' || qstr->name[1]=='.') goto x;
	hpfs_adjust_length(qstr->name, &l);
	/*if (hpfs_chk_name(qstr->name,&l))*/
		/*return -ENAMETOOLONG;*/
		/*return -ENOENT;*/
	x:

	hash = init_name_hash();
	for (i = 0; i < l; i++)
		hash = partial_name_hash(hpfs_upcase(hpfs_sb(dentry->d_sb)->sb_cp_table,qstr->name[i]), hash);
	qstr->hash = end_name_hash(hash);

	return 0;
}

static int hpfs_compare_dentry(const struct dentry *parent,
		const struct inode *pinode,
		const struct dentry *dentry, const struct inode *inode,
		unsigned int len, const char *str, const struct qstr *name)
{
	unsigned al = len;
	unsigned bl = name->len;

	hpfs_adjust_length(str, &al);
	/*hpfs_adjust_length(b->name, &bl);*/

	/*
	 * 'str' is the nane of an already existing dentry, so the name
	 * must be valid. 'name' must be validated first.
	 */

	if (hpfs_chk_name(name->name, &bl))
		return 1;
	if (hpfs_compare_names(parent->d_sb, str, al, name->name, bl, 0))
		return 1;
	return 0;
}

const struct dentry_operations hpfs_dentry_operations = {
	.d_hash		= hpfs_hash_dentry,
	.d_compare	= hpfs_compare_dentry,
};
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