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quota: send messages via netlink 

Implement sending of quota messages via netlink interface.  The advantage
is that in userspace we can better decide what to do with the message - for
example display a dialogue in your X session or just write the message to
the console.  As a bonus, we can get rid of problems with console locking
deep inside filesystem code once we remove the old printing mechanism.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Kara 2007-10-16 23:29:31 -07:00 committed by Linus Torvalds
parent fac8b209b1
commit 8e8934695d
4 changed files with 222 additions and 30 deletions
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59
Documentation/filesystems/quota.txt Normal file
View File

@ -0,0 +1,59 @@
Quota subsystem
===============
Quota subsystem allows system administrator to set limits on used space and
number of used inodes (inode is a filesystem structure which is associated
with each file or directory) for users and/or groups. For both used space and
number of used inodes there are actually two limits. The first one is called
softlimit and the second one hardlimit. An user can never exceed a hardlimit
for any resource. User is allowed to exceed softlimit but only for limited
period of time. This period is called "grace period" or "grace time". When
grace time is over, user is not able to allocate more space/inodes until he
frees enough of them to get below softlimit.
Quota limits (and amount of grace time) are set independently for each
filesystem.
For more details about quota design, see the documentation in quota-tools package
(http://sourceforge.net/projects/linuxquota).
Quota netlink interface
=======================
When user exceeds a softlimit, runs out of grace time or reaches hardlimit,
quota subsystem traditionally printed a message to the controlling terminal of
the process which caused the excess. This method has the disadvantage that
when user is using a graphical desktop he usually cannot see the message.
Thus quota netlink interface has been designed to pass information about
the above events to userspace. There they can be captured by an application
and processed accordingly.
The interface uses generic netlink framework (see
http://lwn.net/Articles/208755/ and http://people.suug.ch/~tgr/libnl/ for more
details about this layer). The name of the quota generic netlink interface
is "VFS_DQUOT". Definitions of constants below are in <linux/quota.h>.
Currently, the interface supports only one message type QUOTA_NL_C_WARNING.
This command is used to send a notification about any of the above mentioned
events. Each message has six attributes. These are (type of the argument is
in parentheses):
QUOTA_NL_A_QTYPE (u32)
- type of quota being exceeded (one of USRQUOTA, GRPQUOTA)
QUOTA_NL_A_EXCESS_ID (u64)
- UID/GID (depends on quota type) of user / group whose limit
is being exceeded.
QUOTA_NL_A_CAUSED_ID (u64)
- UID of a user who caused the event
QUOTA_NL_A_WARNING (u32)
- what kind of limit is exceeded:
QUOTA_NL_IHARDWARN - inode hardlimit
QUOTA_NL_ISOFTLONGWARN - inode softlimit is exceeded longer
than given grace period
QUOTA_NL_ISOFTWARN - inode softlimit
QUOTA_NL_BHARDWARN - space (block) hardlimit
QUOTA_NL_BSOFTLONGWARN - space (block) softlimit is exceeded
longer than given grace period.
QUOTA_NL_BSOFTWARN - space (block) softlimit
QUOTA_NL_A_DEV_MAJOR (u32)
- major number of a device with the affected filesystem
QUOTA_NL_A_DEV_MINOR (u32)
- minor number of a device with the affected filesystem

18
fs/Kconfig
View File

@ -534,6 +534,24 @@ config QUOTA
with the quota tools. Probably the quota support is only useful for
multi user systems. If unsure, say N.
config QUOTA_NETLINK_INTERFACE
bool "Report quota messages through netlink interface"
depends on QUOTA && NET
help
If you say Y here, quota warnings (about exceeding softlimit, reaching
hardlimit, etc.) will be reported through netlink interface. If unsure,
say Y.
config PRINT_QUOTA_WARNING
bool "Print quota warnings to console (OBSOLETE)"
depends on QUOTA
default y
help
If you say Y here, quota warnings (about exceeding softlimit, reaching
hardlimit, etc.) will be printed to the process' controlling terminal.
Note that this behavior is currently deprecated and may go away in
future. Please use notification via netlink socket instead.
config QFMT_V1
tristate "Old quota format support"
depends on QUOTA

144
fs/dquot.c
View File

@ -79,6 +79,10 @@
#include <linux/capability.h>
#include <linux/quotaops.h>
#include <linux/writeback.h> /* for inode_lock, oddly enough.. */
#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
#include <net/netlink.h>
#include <net/genetlink.h>
#endif
#include <asm/uaccess.h>
@ -823,6 +827,7 @@ static inline void dquot_decr_space(struct dquot *dquot, qsize_t number)
clear_bit(DQ_BLKS_B, &dquot->dq_flags);
}
#ifdef CONFIG_PRINT_QUOTA_WARNING
static int flag_print_warnings = 1;
static inline int need_print_warning(struct dquot *dquot)
@ -839,22 +844,15 @@ static inline int need_print_warning(struct dquot *dquot)
return 0;
}
/* Values of warnings */
#define NOWARN 0
#define IHARDWARN 1
#define ISOFTLONGWARN 2
#define ISOFTWARN 3
#define BHARDWARN 4
#define BSOFTLONGWARN 5
#define BSOFTWARN 6
/* Print warning to user which exceeded quota */
static void print_warning(struct dquot *dquot, const char warntype)
{
char *msg = NULL;
struct tty_struct *tty;
int flag = (warntype == BHARDWARN || warntype == BSOFTLONGWARN) ? DQ_BLKS_B :
((warntype == IHARDWARN || warntype == ISOFTLONGWARN) ? DQ_INODES_B : 0);
int flag = (warntype == QUOTA_NL_BHARDWARN ||
warntype == QUOTA_NL_BSOFTLONGWARN) ? DQ_BLKS_B :
((warntype == QUOTA_NL_IHARDWARN ||
warntype == QUOTA_NL_ISOFTLONGWARN) ? DQ_INODES_B : 0);
if (!need_print_warning(dquot) || (flag && test_and_set_bit(flag, &dquot->dq_flags)))
return;
@ -864,28 +862,28 @@ static void print_warning(struct dquot *dquot, const char warntype)
if (!tty)
goto out_lock;
tty_write_message(tty, dquot->dq_sb->s_id);
if (warntype == ISOFTWARN || warntype == BSOFTWARN)
if (warntype == QUOTA_NL_ISOFTWARN || warntype == QUOTA_NL_BSOFTWARN)
tty_write_message(tty, ": warning, ");
else
tty_write_message(tty, ": write failed, ");
tty_write_message(tty, quotatypes[dquot->dq_type]);
switch (warntype) {
case IHARDWARN:
case QUOTA_NL_IHARDWARN:
msg = " file limit reached.\r\n";
break;
case ISOFTLONGWARN:
case QUOTA_NL_ISOFTLONGWARN:
msg = " file quota exceeded too long.\r\n";
break;
case ISOFTWARN:
case QUOTA_NL_ISOFTWARN:
msg = " file quota exceeded.\r\n";
break;
case BHARDWARN:
case QUOTA_NL_BHARDWARN:
msg = " block limit reached.\r\n";
break;
case BSOFTLONGWARN:
case QUOTA_NL_BSOFTLONGWARN:
msg = " block quota exceeded too long.\r\n";
break;
case BSOFTWARN:
case QUOTA_NL_BSOFTWARN:
msg = " block quota exceeded.\r\n";
break;
}
@ -893,14 +891,93 @@ static void print_warning(struct dquot *dquot, const char warntype)
out_lock:
mutex_unlock(&tty_mutex);
}
#endif
#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
/* Size of quota netlink message - actually an upperbound for buffer size */
#define QUOTA_NL_MSG_SIZE 32
/* Netlink family structure for quota */
static struct genl_family quota_genl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = 0,
.name = "VFS_DQUOT",
.version = 1,
.maxattr = QUOTA_NL_A_MAX,
};
/* Send warning to userspace about user which exceeded quota */
static void send_warning(const struct dquot *dquot, const char warntype)
{
static atomic_t seq;
struct sk_buff *skb;
void *msg_head;
int ret;
/* We have to allocate using GFP_NOFS as we are called from a
* filesystem performing write and thus further recursion into
* the fs to free some data could cause deadlocks. */
skb = genlmsg_new(QUOTA_NL_MSG_SIZE, GFP_NOFS);
if (!skb) {
printk(KERN_ERR
"VFS: Not enough memory to send quota warning.\n");
return;
}
msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
&quota_genl_family, 0, QUOTA_NL_C_WARNING);
if (!msg_head) {
printk(KERN_ERR
"VFS: Cannot store netlink header in quota warning.\n");
goto err_out;
}
ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, dquot->dq_type);
if (ret)
goto attr_err_out;
ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, dquot->dq_id);
if (ret)
goto attr_err_out;
ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
if (ret)
goto attr_err_out;
ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR,
MAJOR(dquot->dq_sb->s_dev));
if (ret)
goto attr_err_out;
ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR,
MINOR(dquot->dq_sb->s_dev));
if (ret)
goto attr_err_out;
ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current->user->uid);
if (ret)
goto attr_err_out;
genlmsg_end(skb, msg_head);
ret = genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
if (ret < 0 && ret != -ESRCH)
printk(KERN_ERR
"VFS: Failed to send notification message: %d\n", ret);
return;
attr_err_out:
printk(KERN_ERR "VFS: Failed to compose quota message: %d\n", ret);
err_out:
kfree_skb(skb);
}
#endif
static inline void flush_warnings(struct dquot **dquots, char *warntype)
{
int i;
for (i = 0; i < MAXQUOTAS; i++)
if (dquots[i] != NODQUOT && warntype[i] != NOWARN)
if (dquots[i] != NODQUOT && warntype[i] != QUOTA_NL_NOWARN) {
#ifdef CONFIG_PRINT_QUOTA_WARNING
print_warning(dquots[i], warntype[i]);
#endif
#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
send_warning(dquots[i], warntype[i]);
#endif
}
}
static inline char ignore_hardlimit(struct dquot *dquot)
@ -914,14 +991,14 @@ static inline char ignore_hardlimit(struct dquot *dquot)
/* needs dq_data_lock */
static int check_idq(struct dquot *dquot, ulong inodes, char *warntype)
{
*warntype = NOWARN;
*warntype = QUOTA_NL_NOWARN;
if (inodes <= 0 || test_bit(DQ_FAKE_B, &dquot->dq_flags))
return QUOTA_OK;
if (dquot->dq_dqb.dqb_ihardlimit &&
(dquot->dq_dqb.dqb_curinodes + inodes) > dquot->dq_dqb.dqb_ihardlimit &&
!ignore_hardlimit(dquot)) {
*warntype = IHARDWARN;
*warntype = QUOTA_NL_IHARDWARN;
return NO_QUOTA;
}
@ -929,14 +1006,14 @@ static int check_idq(struct dquot *dquot, ulong inodes, char *warntype)
(dquot->dq_dqb.dqb_curinodes + inodes) > dquot->dq_dqb.dqb_isoftlimit &&
dquot->dq_dqb.dqb_itime && get_seconds() >= dquot->dq_dqb.dqb_itime &&
!ignore_hardlimit(dquot)) {
*warntype = ISOFTLONGWARN;
*warntype = QUOTA_NL_ISOFTLONGWARN;
return NO_QUOTA;
}
if (dquot->dq_dqb.dqb_isoftlimit &&
(dquot->dq_dqb.dqb_curinodes + inodes) > dquot->dq_dqb.dqb_isoftlimit &&
dquot->dq_dqb.dqb_itime == 0) {
*warntype = ISOFTWARN;
*warntype = QUOTA_NL_ISOFTWARN;
dquot->dq_dqb.dqb_itime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_igrace;
}
@ -946,7 +1023,7 @@ static int check_idq(struct dquot *dquot, ulong inodes, char *warntype)
/* needs dq_data_lock */
static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *warntype)
{
*warntype = 0;
*warntype = QUOTA_NL_NOWARN;
if (space <= 0 || test_bit(DQ_FAKE_B, &dquot->dq_flags))
return QUOTA_OK;
@ -954,7 +1031,7 @@ static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *war
toqb(dquot->dq_dqb.dqb_curspace + space) > dquot->dq_dqb.dqb_bhardlimit &&
!ignore_hardlimit(dquot)) {
if (!prealloc)
*warntype = BHARDWARN;
*warntype = QUOTA_NL_BHARDWARN;
return NO_QUOTA;
}
@ -963,7 +1040,7 @@ static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *war
dquot->dq_dqb.dqb_btime && get_seconds() >= dquot->dq_dqb.dqb_btime &&
!ignore_hardlimit(dquot)) {
if (!prealloc)
*warntype = BSOFTLONGWARN;
*warntype = QUOTA_NL_BSOFTLONGWARN;
return NO_QUOTA;
}
@ -971,7 +1048,7 @@ static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *war
toqb(dquot->dq_dqb.dqb_curspace + space) > dquot->dq_dqb.dqb_bsoftlimit &&
dquot->dq_dqb.dqb_btime == 0) {
if (!prealloc) {
*warntype = BSOFTWARN;
*warntype = QUOTA_NL_BSOFTWARN;
dquot->dq_dqb.dqb_btime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_bgrace;
}
else
@ -1066,7 +1143,7 @@ int dquot_alloc_space(struct inode *inode, qsize_t number, int warn)
return QUOTA_OK;
}
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
warntype[cnt] = NOWARN;
warntype[cnt] = QUOTA_NL_NOWARN;
down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
if (IS_NOQUOTA(inode)) { /* Now we can do reliable test... */
@ -1112,7 +1189,7 @@ int dquot_alloc_inode(const struct inode *inode, unsigned long number)
if (IS_NOQUOTA(inode))
return QUOTA_OK;
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
warntype[cnt] = NOWARN;
warntype[cnt] = QUOTA_NL_NOWARN;
down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
if (IS_NOQUOTA(inode)) {
up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
@ -1234,7 +1311,7 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
/* Clear the arrays */
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
transfer_to[cnt] = transfer_from[cnt] = NODQUOT;
warntype[cnt] = NOWARN;
warntype[cnt] = QUOTA_NL_NOWARN;
}
down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
/* Now recheck reliably when holding dqptr_sem */
@ -1808,6 +1885,7 @@ static ctl_table fs_dqstats_table[] = {
.mode = 0444,
.proc_handler = &proc_dointvec,
},
#ifdef CONFIG_PRINT_QUOTA_WARNING
{
.ctl_name = FS_DQ_WARNINGS,
.procname = "warnings",
@ -1816,6 +1894,7 @@ static ctl_table fs_dqstats_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec,
},
#endif
{ .ctl_name = 0 },
};
@ -1877,6 +1956,11 @@ static int __init dquot_init(void)
register_shrinker(&dqcache_shrinker);
#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
if (genl_register_family(&quota_genl_family) != 0)
printk(KERN_ERR "VFS: Failed to create quota netlink interface.\n");
#endif
return 0;
}
module_init(dquot_init);

31
include/linux/quota.h
View File

@ -128,6 +128,37 @@ struct if_dqinfo {
__u32 dqi_valid;
};
/*
* Definitions for quota netlink interface
*/
#define QUOTA_NL_NOWARN 0
#define QUOTA_NL_IHARDWARN 1 /* Inode hardlimit reached */
#define QUOTA_NL_ISOFTLONGWARN 2 /* Inode grace time expired */
#define QUOTA_NL_ISOFTWARN 3 /* Inode softlimit reached */
#define QUOTA_NL_BHARDWARN 4 /* Block hardlimit reached */
#define QUOTA_NL_BSOFTLONGWARN 5 /* Block grace time expired */
#define QUOTA_NL_BSOFTWARN 6 /* Block softlimit reached */
enum {
QUOTA_NL_C_UNSPEC,
QUOTA_NL_C_WARNING,
__QUOTA_NL_C_MAX,
};
#define QUOTA_NL_C_MAX (__QUOTA_NL_C_MAX - 1)
enum {
QUOTA_NL_A_UNSPEC,
QUOTA_NL_A_QTYPE,
QUOTA_NL_A_EXCESS_ID,
QUOTA_NL_A_WARNING,
QUOTA_NL_A_DEV_MAJOR,
QUOTA_NL_A_DEV_MINOR,
QUOTA_NL_A_CAUSED_ID,
__QUOTA_NL_A_MAX,
};
#define QUOTA_NL_A_MAX (__QUOTA_NL_A_MAX - 1)
#ifdef __KERNEL__
#include <linux/spinlock.h>
#include <linux/rwsem.h>