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linux-next/include/linux/quota.h
Al Viro 7b7b1ace2d [PATCH] saner handling of auto_acct_off() and DQUOT_OFF() in umount 
The way we currently deal with quota and process accounting that might
keep vfsmount busy at umount time is inherently broken; we try to turn
them off just in case (not quite correctly, at that) and

  a) pray umount doesn't fail (otherwise they'll stay turned off)
  b) pray nobody doesn anything funny just as we turn quota off

Moreover, LSM provides hooks for doing the same sort of broken logics.

The proper way to deal with that is to introduce the second kind of
reference to vfsmount.  Semantics:

 - when the last normal reference is dropped, all special ones are
   converted to normal ones and if there had been any, cleanup is done.
 - normal reference can be cloned into a special one
 - special reference can be converted to normal one; that's a no-op if
   we'd already passed the point of no return (i.e.  mntput() had
   converted special references to normal and started cleanup).

The way it works: e.g. starting process accounting converts the vfsmount
reference pinned by the opened file into special one and turns it back
to normal when it gets shut down; acct_auto_close() is done when no
normal references are left.  That way it does *not* obstruct umount(2)
and it silently gets turned off when the last normal reference to
vfsmount is gone.  Which is exactly what we want...

The same should be done by LSM module that holds some internal
references to vfsmount and wants to shut them down on umount - it should
make them special and security_sb_umount_close() will be called exactly
when the last normal reference to vfsmount is gone.

quota handling is even simpler - we don't use normal file IO anymore, so
there's no need to hold vfsmounts at all.  DQUOT_OFF() is done from
deactivate_super(), where it really belongs.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 18:18:09 -08:00

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/*
* Copyright (c) 1982, 1986 Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Robert Elz at The University of Melbourne.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* Version: $Id: quota.h,v 2.0 1996/11/17 16:48:14 mvw Exp mvw $
*/
#ifndef _LINUX_QUOTA_
#define _LINUX_QUOTA_
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#define __DQUOT_VERSION__ "dquot_6.5.1"
#define __DQUOT_NUM_VERSION__ 6*10000+5*100+1
typedef __kernel_uid32_t qid_t; /* Type in which we store ids in memory */
typedef __u64 qsize_t; /* Type in which we store sizes */
extern spinlock_t dq_data_lock;
/* Size of blocks in which are counted size limits */
#define QUOTABLOCK_BITS 10
#define QUOTABLOCK_SIZE (1 << QUOTABLOCK_BITS)
/* Conversion routines from and to quota blocks */
#define qb2kb(x) ((x) << (QUOTABLOCK_BITS-10))
#define kb2qb(x) ((x) >> (QUOTABLOCK_BITS-10))
#define toqb(x) (((x) + QUOTABLOCK_SIZE - 1) >> QUOTABLOCK_BITS)
#define MAXQUOTAS 2
#define USRQUOTA 0 /* element used for user quotas */
#define GRPQUOTA 1 /* element used for group quotas */
/*
* Definitions for the default names of the quotas files.
*/
#define INITQFNAMES { \
"user", /* USRQUOTA */ \
"group", /* GRPQUOTA */ \
"undefined", \
};
/*
* Command definitions for the 'quotactl' system call.
* The commands are broken into a main command defined below
* and a subcommand that is used to convey the type of
* quota that is being manipulated (see above).
*/
#define SUBCMDMASK 0x00ff
#define SUBCMDSHIFT 8
#define QCMD(cmd, type) (((cmd) << SUBCMDSHIFT) | ((type) & SUBCMDMASK))
#define Q_SYNC 0x800001 /* sync disk copy of a filesystems quotas */
#define Q_QUOTAON 0x800002 /* turn quotas on */
#define Q_QUOTAOFF 0x800003 /* turn quotas off */
#define Q_GETFMT 0x800004 /* get quota format used on given filesystem */
#define Q_GETINFO 0x800005 /* get information about quota files */
#define Q_SETINFO 0x800006 /* set information about quota files */
#define Q_GETQUOTA 0x800007 /* get user quota structure */
#define Q_SETQUOTA 0x800008 /* set user quota structure */
/*
* Quota structure used for communication with userspace via quotactl
* Following flags are used to specify which fields are valid
*/
#define QIF_BLIMITS 1
#define QIF_SPACE 2
#define QIF_ILIMITS 4
#define QIF_INODES 8
#define QIF_BTIME 16
#define QIF_ITIME 32
#define QIF_LIMITS (QIF_BLIMITS | QIF_ILIMITS)
#define QIF_USAGE (QIF_SPACE | QIF_INODES)
#define QIF_TIMES (QIF_BTIME | QIF_ITIME)
#define QIF_ALL (QIF_LIMITS | QIF_USAGE | QIF_TIMES)
struct if_dqblk {
__u64 dqb_bhardlimit;
__u64 dqb_bsoftlimit;
__u64 dqb_curspace;
__u64 dqb_ihardlimit;
__u64 dqb_isoftlimit;
__u64 dqb_curinodes;
__u64 dqb_btime;
__u64 dqb_itime;
__u32 dqb_valid;
};
/*
* Structure used for setting quota information about file via quotactl
* Following flags are used to specify which fields are valid
*/
#define IIF_BGRACE 1
#define IIF_IGRACE 2
#define IIF_FLAGS 4
#define IIF_ALL (IIF_BGRACE | IIF_IGRACE | IIF_FLAGS)
struct if_dqinfo {
__u64 dqi_bgrace;
__u64 dqi_igrace;
__u32 dqi_flags;
__u32 dqi_valid;
};
#ifdef __KERNEL__
#include <linux/dqblk_xfs.h>
#include <linux/dqblk_v1.h>
#include <linux/dqblk_v2.h>
/* Maximal numbers of writes for quota operation (insert/delete/update)
* (over VFS all formats) */
#define DQUOT_INIT_ALLOC max(V1_INIT_ALLOC, V2_INIT_ALLOC)
#define DQUOT_INIT_REWRITE max(V1_INIT_REWRITE, V2_INIT_REWRITE)
#define DQUOT_DEL_ALLOC max(V1_DEL_ALLOC, V2_DEL_ALLOC)
#define DQUOT_DEL_REWRITE max(V1_DEL_REWRITE, V2_DEL_REWRITE)
/*
* Data for one user/group kept in memory
*/
struct mem_dqblk {
__u32 dqb_bhardlimit; /* absolute limit on disk blks alloc */
__u32 dqb_bsoftlimit; /* preferred limit on disk blks */
qsize_t dqb_curspace; /* current used space */
__u32 dqb_ihardlimit; /* absolute limit on allocated inodes */
__u32 dqb_isoftlimit; /* preferred inode limit */
__u32 dqb_curinodes; /* current # allocated inodes */
time_t dqb_btime; /* time limit for excessive disk use */
time_t dqb_itime; /* time limit for excessive inode use */
};
/*
* Data for one quotafile kept in memory
*/
struct quota_format_type;
struct mem_dqinfo {
struct quota_format_type *dqi_format;
struct list_head dqi_dirty_list; /* List of dirty dquots */
unsigned long dqi_flags;
unsigned int dqi_bgrace;
unsigned int dqi_igrace;
union {
struct v1_mem_dqinfo v1_i;
struct v2_mem_dqinfo v2_i;
} u;
};
struct super_block;
#define DQF_MASK 0xffff /* Mask for format specific flags */
#define DQF_INFO_DIRTY_B 16
#define DQF_INFO_DIRTY (1 << DQF_INFO_DIRTY_B) /* Is info dirty? */
extern void mark_info_dirty(struct super_block *sb, int type);
#define info_dirty(info) test_bit(DQF_INFO_DIRTY_B, &(info)->dqi_flags)
#define info_any_dquot_dirty(info) (!list_empty(&(info)->dqi_dirty_list))
#define info_any_dirty(info) (info_dirty(info) || info_any_dquot_dirty(info))
#define sb_dqopt(sb) (&(sb)->s_dquot)
#define sb_dqinfo(sb, type) (sb_dqopt(sb)->info+(type))
struct dqstats {
int lookups;
int drops;
int reads;
int writes;
int cache_hits;
int allocated_dquots;
int free_dquots;
int syncs;
};
extern struct dqstats dqstats;
#define DQ_MOD_B 0 /* dquot modified since read */
#define DQ_BLKS_B 1 /* uid/gid has been warned about blk limit */
#define DQ_INODES_B 2 /* uid/gid has been warned about inode limit */
#define DQ_FAKE_B 3 /* no limits only usage */
#define DQ_READ_B 4 /* dquot was read into memory */
#define DQ_ACTIVE_B 5 /* dquot is active (dquot_release not called) */
#define DQ_WAITFREE_B 6 /* dquot being waited (by invalidate_dquots) */
struct dquot {
struct hlist_node dq_hash; /* Hash list in memory */
struct list_head dq_inuse; /* List of all quotas */
struct list_head dq_free; /* Free list element */
struct list_head dq_dirty; /* List of dirty dquots */
struct semaphore dq_lock; /* dquot IO lock */
atomic_t dq_count; /* Use count */
wait_queue_head_t dq_wait_unused; /* Wait queue for dquot to become unused */
struct super_block *dq_sb; /* superblock this applies to */
unsigned int dq_id; /* ID this applies to (uid, gid) */
loff_t dq_off; /* Offset of dquot on disk */
unsigned long dq_flags; /* See DQ_* */
short dq_type; /* Type of quota */
struct mem_dqblk dq_dqb; /* Diskquota usage */
};
#define NODQUOT (struct dquot *)NULL
#define QUOTA_OK 0
#define NO_QUOTA 1
/* Operations which must be implemented by each quota format */
struct quota_format_ops {
int (*check_quota_file)(struct super_block *sb, int type); /* Detect whether file is in our format */
int (*read_file_info)(struct super_block *sb, int type); /* Read main info about file - called on quotaon() */
int (*write_file_info)(struct super_block *sb, int type); /* Write main info about file */
int (*free_file_info)(struct super_block *sb, int type); /* Called on quotaoff() */
int (*read_dqblk)(struct dquot *dquot); /* Read structure for one user */
int (*commit_dqblk)(struct dquot *dquot); /* Write structure for one user */
int (*release_dqblk)(struct dquot *dquot); /* Called when last reference to dquot is being dropped */
};
/* Operations working with dquots */
struct dquot_operations {
int (*initialize) (struct inode *, int);
int (*drop) (struct inode *);
int (*alloc_space) (struct inode *, qsize_t, int);
int (*alloc_inode) (const struct inode *, unsigned long);
int (*free_space) (struct inode *, qsize_t);
int (*free_inode) (const struct inode *, unsigned long);
int (*transfer) (struct inode *, struct iattr *);
int (*write_dquot) (struct dquot *); /* Ordinary dquot write */
int (*acquire_dquot) (struct dquot *); /* Quota is going to be created on disk */
int (*release_dquot) (struct dquot *); /* Quota is going to be deleted from disk */
int (*mark_dirty) (struct dquot *); /* Dquot is marked dirty */
int (*write_info) (struct super_block *, int); /* Write of quota "superblock" */
};
/* Operations handling requests from userspace */
struct quotactl_ops {
int (*quota_on)(struct super_block *, int, int, char *);
int (*quota_off)(struct super_block *, int);
int (*quota_sync)(struct super_block *, int);
int (*get_info)(struct super_block *, int, struct if_dqinfo *);
int (*set_info)(struct super_block *, int, struct if_dqinfo *);
int (*get_dqblk)(struct super_block *, int, qid_t, struct if_dqblk *);
int (*set_dqblk)(struct super_block *, int, qid_t, struct if_dqblk *);
int (*get_xstate)(struct super_block *, struct fs_quota_stat *);
int (*set_xstate)(struct super_block *, unsigned int, int);
int (*get_xquota)(struct super_block *, int, qid_t, struct fs_disk_quota *);
int (*set_xquota)(struct super_block *, int, qid_t, struct fs_disk_quota *);
};
struct quota_format_type {
int qf_fmt_id; /* Quota format id */
struct quota_format_ops *qf_ops; /* Operations of format */
struct module *qf_owner; /* Module implementing quota format */
struct quota_format_type *qf_next;
};
#define DQUOT_USR_ENABLED 0x01 /* User diskquotas enabled */
#define DQUOT_GRP_ENABLED 0x02 /* Group diskquotas enabled */
struct quota_info {
unsigned int flags; /* Flags for diskquotas on this device */
struct semaphore dqio_sem; /* lock device while I/O in progress */
struct semaphore dqonoff_sem; /* Serialize quotaon & quotaoff */
struct rw_semaphore dqptr_sem; /* serialize ops using quota_info struct, pointers from inode to dquots */
struct inode *files[MAXQUOTAS]; /* inodes of quotafiles */
struct mem_dqinfo info[MAXQUOTAS]; /* Information for each quota type */
struct quota_format_ops *ops[MAXQUOTAS]; /* Operations for each type */
};
/* Inline would be better but we need to dereference super_block which is not defined yet */
int mark_dquot_dirty(struct dquot *dquot);
#define dquot_dirty(dquot) test_bit(DQ_MOD_B, &(dquot)->dq_flags)
#define sb_has_quota_enabled(sb, type) ((type)==USRQUOTA ? \
(sb_dqopt(sb)->flags & DQUOT_USR_ENABLED) : (sb_dqopt(sb)->flags & DQUOT_GRP_ENABLED))
#define sb_any_quota_enabled(sb) (sb_has_quota_enabled(sb, USRQUOTA) | \
sb_has_quota_enabled(sb, GRPQUOTA))
int register_quota_format(struct quota_format_type *fmt);
void unregister_quota_format(struct quota_format_type *fmt);
struct quota_module_name {
int qm_fmt_id;
char *qm_mod_name;
};
#define INIT_QUOTA_MODULE_NAMES {\
{QFMT_VFS_OLD, "quota_v1"},\
{QFMT_VFS_V0, "quota_v2"},\
{0, NULL}}
#else
# /* nodep */ include <sys/cdefs.h>
__BEGIN_DECLS
long quotactl __P ((unsigned int, const char *, int, caddr_t));
__END_DECLS
#endif /* __KERNEL__ */
#endif /* _QUOTA_ */
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