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>
diff --git a/Documentation/filesystems/quota.txt b/Documentation/filesystems/quota.txt
new file mode 100644
index 0000000..a590c40
--- /dev/null
+++ b/Documentation/filesystems/quota.txt
@@ -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
diff --git a/fs/Kconfig b/fs/Kconfig
index f0df9a2..dc06033 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -534,6 +534,24 @@
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
diff --git a/fs/dquot.c b/fs/dquot.c
index de9a29f6..2809768 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -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 @@
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 @@
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 @@
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 @@
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),
+ "a_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 @@
/* 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 @@
(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 @@
/* 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
/* 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 @@
.mode = 0444,
.proc_handler = &proc_dointvec,
},
+#ifdef CONFIG_PRINT_QUOTA_WARNING
{
.ctl_name = FS_DQ_WARNINGS,
.procname = "warnings",
@@ -1816,6 +1894,7 @@
.mode = 0644,
.proc_handler = &proc_dointvec,
},
+#endif
{ .ctl_name = 0 },
};
@@ -1877,6 +1956,11 @@
register_shrinker(&dqcache_shrinker);
+#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
+ if (genl_register_family("a_genl_family) != 0)
+ printk(KERN_ERR "VFS: Failed to create quota netlink interface.\n");
+#endif
+
return 0;
}
module_init(dquot_init);
diff --git a/include/linux/quota.h b/include/linux/quota.h
index 6243982..6e0393a 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -128,6 +128,37 @@
__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>