/* * Implementation of the diskquota system for the LINUX operating system. QUOTA * is implemented using the BSD system call interface as the means of * communication with the user level. This file contains the generic routines * called by the different filesystems on allocation of an inode or block. * These routines take care of the administration needed to have a consistent * diskquota tracking system. The ideas of both user and group quotas are based * on the Melbourne quota system as used on BSD derived systems. The internal * implementation is based on one of the several variants of the LINUX * inode-subsystem with added complexity of the diskquota system. * * Version: $Id: dquot.c,v 6.3 1996/11/17 18:35:34 mvw Exp mvw $ * * Author: Marco van Wieringen <mvw@planets.elm.net> * * Fixes: Dmitry Gorodchanin <pgmdsg@ibi.com>, 11 Feb 96 * * Revised list management to avoid races * -- Bill Hawes, <whawes@star.net>, 9/98 * * Fixed races in dquot_transfer(), dqget() and dquot_alloc_...(). * As the consequence the locking was moved from dquot_decr_...(), * dquot_incr_...() to calling functions. * invalidate_dquots() now writes modified dquots. * Serialized quota_off() and quota_on() for mount point. * Fixed a few bugs in grow_dquots(). * Fixed deadlock in write_dquot() - we no longer account quotas on * quota files * remove_dquot_ref() moved to inode.c - it now traverses through inodes * add_dquot_ref() restarts after blocking * Added check for bogus uid and fixed check for group in quotactl. * Jan Kara, <jack@suse.cz>, sponsored by SuSE CR, 10-11/99 * * Used struct list_head instead of own list struct * Invalidation of referenced dquots is no longer possible * Improved free_dquots list management * Quota and i_blocks are now updated in one place to avoid races * Warnings are now delayed so we won't block in critical section * Write updated not to require dquot lock * Jan Kara, <jack@suse.cz>, 9/2000 * * Added dynamic quota structure allocation * Jan Kara <jack@suse.cz> 12/2000 * * Rewritten quota interface. Implemented new quota format and * formats registering. * Jan Kara, <jack@suse.cz>, 2001,2002 * * New SMP locking. * Jan Kara, <jack@suse.cz>, 10/2002 * * Added journalled quota support, fix lock inversion problems * Jan Kara, <jack@suse.cz>, 2003,2004 * * (C) Copyright 1994 - 1997 Marco van Wieringen */ #include <linux/errno.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/mount.h> #include <linux/mm.h> #include <linux/time.h> #include <linux/types.h> #include <linux/string.h> #include <linux/fcntl.h> #include <linux/stat.h> #include <linux/tty.h> #include <linux/file.h> #include <linux/slab.h> #include <linux/sysctl.h> #include <linux/init.h> #include <linux/module.h> #include <linux/proc_fs.h> #include <linux/security.h> #include <linux/kmod.h> #include <linux/namei.h> #include <linux/buffer_head.h> #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> #define __DQUOT_PARANOIA /* * There are two quota SMP locks. dq_list_lock protects all lists with quotas * and quota formats and also dqstats structure containing statistics about the * lists. dq_data_lock protects data from dq_dqb and also mem_dqinfo structures * and also guards consistency of dquot->dq_dqb with inode->i_blocks, i_bytes. * i_blocks and i_bytes updates itself are guarded by i_lock acquired directly * in inode_add_bytes() and inode_sub_bytes(). * * The spinlock ordering is hence: dq_data_lock > dq_list_lock > i_lock * * Note that some things (eg. sb pointer, type, id) doesn't change during * the life of the dquot structure and so needn't to be protected by a lock * * Any operation working on dquots via inode pointers must hold dqptr_sem. If * operation is just reading pointers from inode (or not using them at all) the * read lock is enough. If pointers are altered function must hold write lock * (these locking rules also apply for S_NOQUOTA flag in the inode - note that * for altering the flag i_mutex is also needed). If operation is holding * reference to dquot in other way (e.g. quotactl ops) it must be guarded by * dqonoff_mutex. * This locking assures that: * a) update/access to dquot pointers in inode is serialized * b) everyone is guarded against invalidate_dquots() * * Each dquot has its dq_lock mutex. Locked dquots might not be referenced * from inodes (dquot_alloc_space() and such don't check the dq_lock). * Currently dquot is locked only when it is being read to memory (or space for * it is being allocated) on the first dqget() and when it is being released on * the last dqput(). The allocation and release oparations are serialized by * the dq_lock and by checking the use count in dquot_release(). Write * operations on dquots don't hold dq_lock as they copy data under dq_data_lock * spinlock to internal buffers before writing. * * Lock ordering (including related VFS locks) is the following: * i_mutex > dqonoff_sem > journal_lock > dqptr_sem > dquot->dq_lock > * dqio_mutex * i_mutex on quota files is special (it's below dqio_mutex) */ static DEFINE_SPINLOCK(dq_list_lock); DEFINE_SPINLOCK(dq_data_lock); static char *quotatypes[] = INITQFNAMES; static struct quota_format_type *quota_formats; /* List of registered formats */ static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES; /* SLAB cache for dquot structures */ static struct kmem_cache *dquot_cachep; int register_quota_format(struct quota_format_type *fmt) { spin_lock(&dq_list_lock); fmt->qf_next = quota_formats; quota_formats = fmt; spin_unlock(&dq_list_lock); return 0; } void unregister_quota_format(struct quota_format_type *fmt) { struct quota_format_type **actqf; spin_lock(&dq_list_lock); for (actqf = "a_formats; *actqf && *actqf != fmt; actqf = &(*actqf)->qf_next); if (*actqf) *actqf = (*actqf)->qf_next; spin_unlock(&dq_list_lock); } static struct quota_format_type *find_quota_format(int id) { struct quota_format_type *actqf; spin_lock(&dq_list_lock); for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id; actqf = actqf->qf_next); if (!actqf || !try_module_get(actqf->qf_owner)) { int qm; spin_unlock(&dq_list_lock); for (qm = 0; module_names[qm].qm_fmt_id && module_names[qm].qm_fmt_id != id; qm++); if (!module_names[qm].qm_fmt_id || request_module(module_names[qm].qm_mod_name)) return NULL; spin_lock(&dq_list_lock); for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id; actqf = actqf->qf_next); if (actqf && !try_module_get(actqf->qf_owner)) actqf = NULL; } spin_unlock(&dq_list_lock); return actqf; } static void put_quota_format(struct quota_format_type *fmt) { module_put(fmt->qf_owner); } /* * Dquot List Management: * The quota code uses three lists for dquot management: the inuse_list, * free_dquots, and dquot_hash[] array. A single dquot structure may be * on all three lists, depending on its current state. * * All dquots are placed to the end of inuse_list when first created, and this * list is used for invalidate operation, which must look at every dquot. * * Unused dquots (dq_count == 0) are added to the free_dquots list when freed, * and this list is searched whenever we need an available dquot. Dquots are * removed from the list as soon as they are used again, and * dqstats.free_dquots gives the number of dquots on the list. When * dquot is invalidated it's completely released from memory. * * Dquots with a specific identity (device, type and id) are placed on * one of the dquot_hash[] hash chains. The provides an efficient search * mechanism to locate a specific dquot. */ static LIST_HEAD(inuse_list); static LIST_HEAD(free_dquots); static unsigned int dq_hash_bits, dq_hash_mask; static struct hlist_head *dquot_hash; struct dqstats dqstats; static void dqput(struct dquot *dquot); static inline unsigned int hashfn(const struct super_block *sb, unsigned int id, int type) { unsigned long tmp; tmp = (((unsigned long)sb>>L1_CACHE_SHIFT) ^ id) * (MAXQUOTAS - type); return (tmp + (tmp >> dq_hash_bits)) & dq_hash_mask; } /* * Following list functions expect dq_list_lock to be held */ static inline void insert_dquot_hash(struct dquot *dquot) { struct hlist_head *head = dquot_hash + hashfn(dquot->dq_sb, dquot->dq_id, dquot->dq_type); hlist_add_head(&dquot->dq_hash, head); } static inline void remove_dquot_hash(struct dquot *dquot) { hlist_del_init(&dquot->dq_hash); } static inline struct dquot *find_dquot(unsigned int hashent, struct super_block *sb, unsigned int id, int type) { struct hlist_node *node; struct dquot *dquot; hlist_for_each (node, dquot_hash+hashent) { dquot = hlist_entry(node, struct dquot, dq_hash); if (dquot->dq_sb == sb && dquot->dq_id == id && dquot->dq_type == type) return dquot; } return NODQUOT; } /* Add a dquot to the tail of the free list */ static inline void put_dquot_last(struct dquot *dquot) { list_add_tail(&dquot->dq_free, &free_dquots); dqstats.free_dquots++; } static inline void remove_free_dquot(struct dquot *dquot) { if (list_empty(&dquot->dq_free)) return; list_del_init(&dquot->dq_free); dqstats.free_dquots--; } static inline void put_inuse(struct dquot *dquot) { /* We add to the back of inuse list so we don't have to restart * when traversing this list and we block */ list_add_tail(&dquot->dq_inuse, &inuse_list); dqstats.allocated_dquots++; } static inline void remove_inuse(struct dquot *dquot) { dqstats.allocated_dquots--; list_del(&dquot->dq_inuse); } /* * End of list functions needing dq_list_lock */ static void wait_on_dquot(struct dquot *dquot) { mutex_lock(&dquot->dq_lock); mutex_unlock(&dquot->dq_lock); } static inline int dquot_dirty(struct dquot *dquot) { return test_bit(DQ_MOD_B, &dquot->dq_flags); } static inline int mark_dquot_dirty(struct dquot *dquot) { return dquot->dq_sb->dq_op->mark_dirty(dquot); } int dquot_mark_dquot_dirty(struct dquot *dquot) { spin_lock(&dq_list_lock); if (!test_and_set_bit(DQ_MOD_B, &dquot->dq_flags)) list_add(&dquot->dq_dirty, &sb_dqopt(dquot->dq_sb)-> info[dquot->dq_type].dqi_dirty_list); spin_unlock(&dq_list_lock); return 0; } /* This function needs dq_list_lock */ static inline int clear_dquot_dirty(struct dquot *dquot) { if (!test_and_clear_bit(DQ_MOD_B, &dquot->dq_flags)) return 0; list_del_init(&dquot->dq_dirty); return 1; } void mark_info_dirty(struct super_block *sb, int type) { set_bit(DQF_INFO_DIRTY_B, &sb_dqopt(sb)->info[type].dqi_flags); } EXPORT_SYMBOL(mark_info_dirty); /* * Read dquot from disk and alloc space for it */ int dquot_acquire(struct dquot *dquot) { int ret = 0, ret2 = 0; struct quota_info *dqopt = sb_dqopt(dquot->dq_sb); mutex_lock(&dquot->dq_lock); mutex_lock(&dqopt->dqio_mutex); if (!test_bit(DQ_READ_B, &dquot->dq_flags)) ret = dqopt->ops[dquot->dq_type]->read_dqblk(dquot); if (ret < 0) goto out_iolock; set_bit(DQ_READ_B, &dquot->dq_flags); /* Instantiate dquot if needed */ if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) { ret = dqopt->ops[dquot->dq_type]->commit_dqblk(dquot); /* Write the info if needed */ if (info_dirty(&dqopt->info[dquot->dq_type])) ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type); if (ret < 0) goto out_iolock; if (ret2 < 0) { ret = ret2; goto out_iolock; } } set_bit(DQ_ACTIVE_B, &dquot->dq_flags); out_iolock: mutex_unlock(&dqopt->dqio_mutex); mutex_unlock(&dquot->dq_lock); return ret; } /* * Write dquot to disk */ int dquot_commit(struct dquot *dquot) { int ret = 0, ret2 = 0; struct quota_info *dqopt = sb_dqopt(dquot->dq_sb); mutex_lock(&dqopt->dqio_mutex); spin_lock(&dq_list_lock); if (!clear_dquot_dirty(dquot)) { spin_unlock(&dq_list_lock); goto out_sem; } spin_unlock(&dq_list_lock); /* Inactive dquot can be only if there was error during read/init * => we have better not writing it */ if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { ret = dqopt->ops[dquot->dq_type]->commit_dqblk(dquot); if (info_dirty(&dqopt->info[dquot->dq_type])) ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type); if (ret >= 0) ret = ret2; } out_sem: mutex_unlock(&dqopt->dqio_mutex); return ret; } /* * Release dquot */ int dquot_release(struct dquot *dquot) { int ret = 0, ret2 = 0; struct quota_info *dqopt = sb_dqopt(dquot->dq_sb); mutex_lock(&dquot->dq_lock); /* Check whether we are not racing with some other dqget() */ if (atomic_read(&dquot->dq_count) > 1) goto out_dqlock; mutex_lock(&dqopt->dqio_mutex); if (dqopt->ops[dquot->dq_type]->release_dqblk) { ret = dqopt->ops[dquot->dq_type]->release_dqblk(dquot); /* Write the info */ if (info_dirty(&dqopt->info[dquot->dq_type])) ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type); if (ret >= 0) ret = ret2; } clear_bit(DQ_ACTIVE_B, &dquot->dq_flags); mutex_unlock(&dqopt->dqio_mutex); out_dqlock: mutex_unlock(&dquot->dq_lock); return ret; } /* Invalidate all dquots on the list. Note that this function is called after * quota is disabled and pointers from inodes removed so there cannot be new * quota users. There can still be some users of quotas due to inodes being * just deleted or pruned by prune_icache() (those are not attached to any * list). We have to wait for such users. */ static void invalidate_dquots(struct super_block *sb, int type) { struct dquot *dquot, *tmp; restart: spin_lock(&dq_list_lock); list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) { if (dquot->dq_sb != sb) continue; if (dquot->dq_type != type) continue; /* Wait for dquot users */ if (atomic_read(&dquot->dq_count)) { DEFINE_WAIT(wait); atomic_inc(&dquot->dq_count); prepare_to_wait(&dquot->dq_wait_unused, &wait, TASK_UNINTERRUPTIBLE); spin_unlock(&dq_list_lock); /* Once dqput() wakes us up, we know it's time to free * the dquot. * IMPORTANT: we rely on the fact that there is always * at most one process waiting for dquot to free. * Otherwise dq_count would be > 1 and we would never * wake up. */ if (atomic_read(&dquot->dq_count) > 1) schedule(); finish_wait(&dquot->dq_wait_unused, &wait); dqput(dquot); /* At this moment dquot() need not exist (it could be * reclaimed by prune_dqcache(). Hence we must * restart. */ goto restart; } /* * Quota now has no users and it has been written on last * dqput() */ remove_dquot_hash(dquot); remove_free_dquot(dquot); remove_inuse(dquot); kmem_cache_free(dquot_cachep, dquot); } spin_unlock(&dq_list_lock); } int vfs_quota_sync(struct super_block *sb, int type) { struct list_head *dirty; struct dquot *dquot; struct quota_info *dqopt = sb_dqopt(sb); int cnt; mutex_lock(&dqopt->dqonoff_mutex); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (type != -1 && cnt != type) continue; if (!sb_has_quota_enabled(sb, cnt)) continue; spin_lock(&dq_list_lock); dirty = &dqopt->info[cnt].dqi_dirty_list; while (!list_empty(dirty)) { dquot = list_first_entry(dirty, struct dquot, dq_dirty); /* Dirty and inactive can be only bad dquot... */ if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { clear_dquot_dirty(dquot); continue; } /* Now we have active dquot from which someone is * holding reference so we can safely just increase * use count */ atomic_inc(&dquot->dq_count); dqstats.lookups++; spin_unlock(&dq_list_lock); sb->dq_op->write_dquot(dquot); dqput(dquot); spin_lock(&dq_list_lock); } spin_unlock(&dq_list_lock); } for (cnt = 0; cnt < MAXQUOTAS; cnt++) if ((cnt == type || type == -1) && sb_has_quota_enabled(sb, cnt) && info_dirty(&dqopt->info[cnt])) sb->dq_op->write_info(sb, cnt); spin_lock(&dq_list_lock); dqstats.syncs++; spin_unlock(&dq_list_lock); mutex_unlock(&dqopt->dqonoff_mutex); return 0; } /* Free unused dquots from cache */ static void prune_dqcache(int count) { struct list_head *head; struct dquot *dquot; head = free_dquots.prev; while (head != &free_dquots && count) { dquot = list_entry(head, struct dquot, dq_free); remove_dquot_hash(dquot); remove_free_dquot(dquot); remove_inuse(dquot); kmem_cache_free(dquot_cachep, dquot); count--; head = free_dquots.prev; } } /* * This is called from kswapd when we think we need some * more memory */ static int shrink_dqcache_memory(int nr, gfp_t gfp_mask) { if (nr) { spin_lock(&dq_list_lock); prune_dqcache(nr); spin_unlock(&dq_list_lock); } return (dqstats.free_dquots / 100) * sysctl_vfs_cache_pressure; } static struct shrinker dqcache_shrinker = { .shrink = shrink_dqcache_memory, .seeks = DEFAULT_SEEKS, }; /* * Put reference to dquot * NOTE: If you change this function please check whether dqput_blocks() works right... * MUST be called with either dqptr_sem or dqonoff_mutex held */ static void dqput(struct dquot *dquot) { int ret; if (!dquot) return; #ifdef __DQUOT_PARANOIA if (!atomic_read(&dquot->dq_count)) { printk("VFS: dqput: trying to free free dquot\n"); printk("VFS: device %s, dquot of %s %d\n", dquot->dq_sb->s_id, quotatypes[dquot->dq_type], dquot->dq_id); BUG(); } #endif spin_lock(&dq_list_lock); dqstats.drops++; spin_unlock(&dq_list_lock); we_slept: spin_lock(&dq_list_lock); if (atomic_read(&dquot->dq_count) > 1) { /* We have more than one user... nothing to do */ atomic_dec(&dquot->dq_count); /* Releasing dquot during quotaoff phase? */ if (!sb_has_quota_enabled(dquot->dq_sb, dquot->dq_type) && atomic_read(&dquot->dq_count) == 1) wake_up(&dquot->dq_wait_unused); spin_unlock(&dq_list_lock); return; } /* Need to release dquot? */ if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && dquot_dirty(dquot)) { spin_unlock(&dq_list_lock); /* Commit dquot before releasing */ ret = dquot->dq_sb->dq_op->write_dquot(dquot); if (ret < 0) { printk(KERN_ERR "VFS: cannot write quota structure on " "device %s (error %d). Quota may get out of " "sync!\n", dquot->dq_sb->s_id, ret); /* * We clear dirty bit anyway, so that we avoid * infinite loop here */ spin_lock(&dq_list_lock); clear_dquot_dirty(dquot); spin_unlock(&dq_list_lock); } goto we_slept; } /* Clear flag in case dquot was inactive (something bad happened) */ clear_dquot_dirty(dquot); if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { spin_unlock(&dq_list_lock); dquot->dq_sb->dq_op->release_dquot(dquot); goto we_slept; } atomic_dec(&dquot->dq_count); #ifdef __DQUOT_PARANOIA /* sanity check */ BUG_ON(!list_empty(&dquot->dq_free)); #endif put_dquot_last(dquot); spin_unlock(&dq_list_lock); } static struct dquot *get_empty_dquot(struct super_block *sb, int type) { struct dquot *dquot; dquot = kmem_cache_zalloc(dquot_cachep, GFP_NOFS); if(!dquot) return NODQUOT; mutex_init(&dquot->dq_lock); INIT_LIST_HEAD(&dquot->dq_free); INIT_LIST_HEAD(&dquot->dq_inuse); INIT_HLIST_NODE(&dquot->dq_hash); INIT_LIST_HEAD(&dquot->dq_dirty); init_waitqueue_head(&dquot->dq_wait_unused); dquot->dq_sb = sb; dquot->dq_type = type; atomic_set(&dquot->dq_count, 1); return dquot; } /* * Get reference to dquot * MUST be called with either dqptr_sem or dqonoff_mutex held */ static struct dquot *dqget(struct super_block *sb, unsigned int id, int type) { unsigned int hashent = hashfn(sb, id, type); struct dquot *dquot, *empty = NODQUOT; if (!sb_has_quota_enabled(sb, type)) return NODQUOT; we_slept: spin_lock(&dq_list_lock); if ((dquot = find_dquot(hashent, sb, id, type)) == NODQUOT) { if (empty == NODQUOT) { spin_unlock(&dq_list_lock); if ((empty = get_empty_dquot(sb, type)) == NODQUOT) schedule(); /* Try to wait for a moment... */ goto we_slept; } dquot = empty; dquot->dq_id = id; /* all dquots go on the inuse_list */ put_inuse(dquot); /* hash it first so it can be found */ insert_dquot_hash(dquot); dqstats.lookups++; spin_unlock(&dq_list_lock); } else { if (!atomic_read(&dquot->dq_count)) remove_free_dquot(dquot); atomic_inc(&dquot->dq_count); dqstats.cache_hits++; dqstats.lookups++; spin_unlock(&dq_list_lock); if (empty) kmem_cache_free(dquot_cachep, empty); } /* Wait for dq_lock - after this we know that either dquot_release() is already * finished or it will be canceled due to dq_count > 1 test */ wait_on_dquot(dquot); /* Read the dquot and instantiate it (everything done only if needed) */ if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && sb->dq_op->acquire_dquot(dquot) < 0) { dqput(dquot); return NODQUOT; } #ifdef __DQUOT_PARANOIA BUG_ON(!dquot->dq_sb); /* Has somebody invalidated entry under us? */ #endif return dquot; } static int dqinit_needed(struct inode *inode, int type) { int cnt; if (IS_NOQUOTA(inode)) return 0; if (type != -1) return inode->i_dquot[type] == NODQUOT; for (cnt = 0; cnt < MAXQUOTAS; cnt++) if (inode->i_dquot[cnt] == NODQUOT) return 1; return 0; } /* This routine is guarded by dqonoff_mutex mutex */ static void add_dquot_ref(struct super_block *sb, int type) { struct inode *inode, *old_inode = NULL; spin_lock(&inode_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { if (!atomic_read(&inode->i_writecount)) continue; if (!dqinit_needed(inode, type)) continue; if (inode->i_state & (I_FREEING|I_WILL_FREE)) continue; __iget(inode); spin_unlock(&inode_lock); iput(old_inode); sb->dq_op->initialize(inode, type); /* We hold a reference to 'inode' so it couldn't have been * removed from s_inodes list while we dropped the inode_lock. * We cannot iput the inode now as we can be holding the last * reference and we cannot iput it under inode_lock. So we * keep the reference and iput it later. */ old_inode = inode; spin_lock(&inode_lock); } spin_unlock(&inode_lock); iput(old_inode); } /* Return 0 if dqput() won't block (note that 1 doesn't necessarily mean blocking) */ static inline int dqput_blocks(struct dquot *dquot) { if (atomic_read(&dquot->dq_count) <= 1) return 1; return 0; } /* Remove references to dquots from inode - add dquot to list for freeing if needed */ /* We can't race with anybody because we hold dqptr_sem for writing... */ static int remove_inode_dquot_ref(struct inode *inode, int type, struct list_head *tofree_head) { struct dquot *dquot = inode->i_dquot[type]; inode->i_dquot[type] = NODQUOT; if (dquot != NODQUOT) { if (dqput_blocks(dquot)) { #ifdef __DQUOT_PARANOIA if (atomic_read(&dquot->dq_count) != 1) printk(KERN_WARNING "VFS: Adding dquot with dq_count %d to dispose list.\n", atomic_read(&dquot->dq_count)); #endif spin_lock(&dq_list_lock); list_add(&dquot->dq_free, tofree_head); /* As dquot must have currently users it can't be on the free list... */ spin_unlock(&dq_list_lock); return 1; } else dqput(dquot); /* We have guaranteed we won't block */ } return 0; } /* Free list of dquots - called from inode.c */ /* dquots are removed from inodes, no new references can be got so we are the only ones holding reference */ static void put_dquot_list(struct list_head *tofree_head) { struct list_head *act_head; struct dquot *dquot; act_head = tofree_head->next; /* So now we have dquots on the list... Just free them */ while (act_head != tofree_head) { dquot = list_entry(act_head, struct dquot, dq_free); act_head = act_head->next; list_del_init(&dquot->dq_free); /* Remove dquot from the list so we won't have problems... */ dqput(dquot); } } static void remove_dquot_ref(struct super_block *sb, int type, struct list_head *tofree_head) { struct inode *inode; spin_lock(&inode_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { if (!IS_NOQUOTA(inode)) remove_inode_dquot_ref(inode, type, tofree_head); } spin_unlock(&inode_lock); } /* Gather all references from inodes and drop them */ static void drop_dquot_ref(struct super_block *sb, int type) { LIST_HEAD(tofree_head); if (sb->dq_op) { down_write(&sb_dqopt(sb)->dqptr_sem); remove_dquot_ref(sb, type, &tofree_head); up_write(&sb_dqopt(sb)->dqptr_sem); put_dquot_list(&tofree_head); } } static inline void dquot_incr_inodes(struct dquot *dquot, unsigned long number) { dquot->dq_dqb.dqb_curinodes += number; } static inline void dquot_incr_space(struct dquot *dquot, qsize_t number) { dquot->dq_dqb.dqb_curspace += number; } static inline void dquot_decr_inodes(struct dquot *dquot, unsigned long number) { if (dquot->dq_dqb.dqb_curinodes > number) dquot->dq_dqb.dqb_curinodes -= number; else dquot->dq_dqb.dqb_curinodes = 0; if (dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit) dquot->dq_dqb.dqb_itime = (time_t) 0; clear_bit(DQ_INODES_B, &dquot->dq_flags); } static inline void dquot_decr_space(struct dquot *dquot, qsize_t number) { if (dquot->dq_dqb.dqb_curspace > number) dquot->dq_dqb.dqb_curspace -= number; else dquot->dq_dqb.dqb_curspace = 0; if (toqb(dquot->dq_dqb.dqb_curspace) <= dquot->dq_dqb.dqb_bsoftlimit) dquot->dq_dqb.dqb_btime = (time_t) 0; clear_bit(DQ_BLKS_B, &dquot->dq_flags); } static int warning_issued(struct dquot *dquot, const int warntype) { 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 (!flag) return 0; return test_and_set_bit(flag, &dquot->dq_flags); } #ifdef CONFIG_PRINT_QUOTA_WARNING static int flag_print_warnings = 1; static inline int need_print_warning(struct dquot *dquot) { if (!flag_print_warnings) return 0; switch (dquot->dq_type) { case USRQUOTA: return current->fsuid == dquot->dq_id; case GRPQUOTA: return in_group_p(dquot->dq_id); } return 0; } /* Print warning to user which exceeded quota */ static void print_warning(struct dquot *dquot, const int warntype) { char *msg = NULL; struct tty_struct *tty; if (warntype == QUOTA_NL_IHARDBELOW || warntype == QUOTA_NL_ISOFTBELOW || warntype == QUOTA_NL_BHARDBELOW || warntype == QUOTA_NL_BSOFTBELOW || !need_print_warning(dquot)) return; mutex_lock(&tty_mutex); tty = get_current_tty(); if (!tty) goto out_lock; tty_write_message(tty, dquot->dq_sb->s_id); 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 QUOTA_NL_IHARDWARN: msg = " file limit reached.\r\n"; break; case QUOTA_NL_ISOFTLONGWARN: msg = " file quota exceeded too long.\r\n"; break; case QUOTA_NL_ISOFTWARN: msg = " file quota exceeded.\r\n"; break; case QUOTA_NL_BHARDWARN: msg = " block limit reached.\r\n"; break; case QUOTA_NL_BSOFTLONGWARN: msg = " block quota exceeded too long.\r\n"; break; case QUOTA_NL_BSOFTWARN: msg = " block quota exceeded.\r\n"; break; } tty_write_message(tty, msg); out_lock: mutex_unlock(&tty_mutex); } #endif #ifdef CONFIG_QUOTA_NETLINK_INTERFACE /* 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; int msg_size = 4 * nla_total_size(sizeof(u32)) + 2 * nla_total_size(sizeof(u64)); /* 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(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: Not enough space to compose quota message!\n"); err_out: kfree_skb(skb); } #endif static inline void flush_warnings(struct dquot * const *dquots, char *warntype) { int i; for (i = 0; i < MAXQUOTAS; i++) if (dquots[i] != NODQUOT && warntype[i] != QUOTA_NL_NOWARN && !warning_issued(dquots[i], warntype[i])) { #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) { struct mem_dqinfo *info = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_type]; return capable(CAP_SYS_RESOURCE) && (info->dqi_format->qf_fmt_id != QFMT_VFS_OLD || !(info->dqi_flags & V1_DQF_RSQUASH)); } /* needs dq_data_lock */ static int check_idq(struct dquot *dquot, ulong inodes, char *warntype) { *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 = QUOTA_NL_IHARDWARN; 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 && get_seconds() >= dquot->dq_dqb.dqb_itime && !ignore_hardlimit(dquot)) { *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 = QUOTA_NL_ISOFTWARN; dquot->dq_dqb.dqb_itime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_igrace; } return QUOTA_OK; } /* needs dq_data_lock */ static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *warntype) { *warntype = QUOTA_NL_NOWARN; if (space <= 0 || test_bit(DQ_FAKE_B, &dquot->dq_flags)) return QUOTA_OK; if (dquot->dq_dqb.dqb_bhardlimit && toqb(dquot->dq_dqb.dqb_curspace + space) > dquot->dq_dqb.dqb_bhardlimit && !ignore_hardlimit(dquot)) { if (!prealloc) *warntype = QUOTA_NL_BHARDWARN; return NO_QUOTA; } if (dquot->dq_dqb.dqb_bsoftlimit && toqb(dquot->dq_dqb.dqb_curspace + space) > dquot->dq_dqb.dqb_bsoftlimit && dquot->dq_dqb.dqb_btime && get_seconds() >= dquot->dq_dqb.dqb_btime && !ignore_hardlimit(dquot)) { if (!prealloc) *warntype = QUOTA_NL_BSOFTLONGWARN; return NO_QUOTA; } if (dquot->dq_dqb.dqb_bsoftlimit && toqb(dquot->dq_dqb.dqb_curspace + space) > dquot->dq_dqb.dqb_bsoftlimit && dquot->dq_dqb.dqb_btime == 0) { if (!prealloc) { *warntype = QUOTA_NL_BSOFTWARN; dquot->dq_dqb.dqb_btime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_bgrace; } else /* * We don't allow preallocation to exceed softlimit so exceeding will * be always printed */ return NO_QUOTA; } return QUOTA_OK; } static int info_idq_free(struct dquot *dquot, ulong inodes) { if (test_bit(DQ_FAKE_B, &dquot->dq_flags) || dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit) return QUOTA_NL_NOWARN; if (dquot->dq_dqb.dqb_curinodes - inodes <= dquot->dq_dqb.dqb_isoftlimit) return QUOTA_NL_ISOFTBELOW; if (dquot->dq_dqb.dqb_curinodes >= dquot->dq_dqb.dqb_ihardlimit && dquot->dq_dqb.dqb_curinodes - inodes < dquot->dq_dqb.dqb_ihardlimit) return QUOTA_NL_IHARDBELOW; return QUOTA_NL_NOWARN; } static int info_bdq_free(struct dquot *dquot, qsize_t space) { if (test_bit(DQ_FAKE_B, &dquot->dq_flags) || toqb(dquot->dq_dqb.dqb_curspace) <= dquot->dq_dqb.dqb_bsoftlimit) return QUOTA_NL_NOWARN; if (toqb(dquot->dq_dqb.dqb_curspace - space) <= dquot->dq_dqb.dqb_bsoftlimit) return QUOTA_NL_BSOFTBELOW; if (toqb(dquot->dq_dqb.dqb_curspace) >= dquot->dq_dqb.dqb_bhardlimit && toqb(dquot->dq_dqb.dqb_curspace - space) < dquot->dq_dqb.dqb_bhardlimit) return QUOTA_NL_BHARDBELOW; return QUOTA_NL_NOWARN; } /* * Initialize quota pointers in inode * Transaction must be started at entry */ int dquot_initialize(struct inode *inode, int type) { unsigned int id = 0; int cnt, ret = 0; /* First test before acquiring mutex - solves deadlocks when we * re-enter the quota code and are already holding the mutex */ if (IS_NOQUOTA(inode)) return 0; down_write(&sb_dqopt(inode->i_sb)->dqptr_sem); /* Having dqptr_sem we know NOQUOTA flags can't be altered... */ if (IS_NOQUOTA(inode)) goto out_err; for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (type != -1 && cnt != type) continue; if (inode->i_dquot[cnt] == NODQUOT) { switch (cnt) { case USRQUOTA: id = inode->i_uid; break; case GRPQUOTA: id = inode->i_gid; break; } inode->i_dquot[cnt] = dqget(inode->i_sb, id, cnt); } } out_err: up_write(&sb_dqopt(inode->i_sb)->dqptr_sem); return ret; } /* * Release all quotas referenced by inode * Transaction must be started at an entry */ int dquot_drop(struct inode *inode) { int cnt; down_write(&sb_dqopt(inode->i_sb)->dqptr_sem); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (inode->i_dquot[cnt] != NODQUOT) { dqput(inode->i_dquot[cnt]); inode->i_dquot[cnt] = NODQUOT; } } up_write(&sb_dqopt(inode->i_sb)->dqptr_sem); return 0; } /* Wrapper to remove references to quota structures from inode */ void vfs_dq_drop(struct inode *inode) { /* Here we can get arbitrary inode from clear_inode() so we have * to be careful. OTOH we don't need locking as quota operations * are allowed to change only at mount time */ if (!IS_NOQUOTA(inode) && inode->i_sb && inode->i_sb->dq_op && inode->i_sb->dq_op->drop) { int cnt; /* Test before calling to rule out calls from proc and such * where we are not allowed to block. Note that this is * actually reliable test even without the lock - the caller * must assure that nobody can come after the DQUOT_DROP and * add quota pointers back anyway */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) if (inode->i_dquot[cnt] != NODQUOT) break; if (cnt < MAXQUOTAS) inode->i_sb->dq_op->drop(inode); } } /* * Following four functions update i_blocks+i_bytes fields and * quota information (together with appropriate checks) * NOTE: We absolutely rely on the fact that caller dirties * the inode (usually macros in quotaops.h care about this) and * holds a handle for the current transaction so that dquot write and * inode write go into the same transaction. */ /* * This operation can block, but only after everything is updated */ int dquot_alloc_space(struct inode *inode, qsize_t number, int warn) { int cnt, ret = NO_QUOTA; char warntype[MAXQUOTAS]; /* First test before acquiring mutex - solves deadlocks when we * re-enter the quota code and are already holding the mutex */ if (IS_NOQUOTA(inode)) { out_add: inode_add_bytes(inode, number); return QUOTA_OK; } for (cnt = 0; cnt < MAXQUOTAS; cnt++) warntype[cnt] = QUOTA_NL_NOWARN; down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); if (IS_NOQUOTA(inode)) { /* Now we can do reliable test... */ up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); goto out_add; } spin_lock(&dq_data_lock); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (inode->i_dquot[cnt] == NODQUOT) continue; if (check_bdq(inode->i_dquot[cnt], number, warn, warntype+cnt) == NO_QUOTA) goto warn_put_all; } for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (inode->i_dquot[cnt] == NODQUOT) continue; dquot_incr_space(inode->i_dquot[cnt], number); } inode_add_bytes(inode, number); ret = QUOTA_OK; warn_put_all: spin_unlock(&dq_data_lock); if (ret == QUOTA_OK) /* Dirtify all the dquots - this can block when journalling */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) if (inode->i_dquot[cnt]) mark_dquot_dirty(inode->i_dquot[cnt]); flush_warnings(inode->i_dquot, warntype); up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); return ret; } /* * This operation can block, but only after everything is updated */ int dquot_alloc_inode(const struct inode *inode, unsigned long number) { int cnt, ret = NO_QUOTA; char warntype[MAXQUOTAS]; /* First test before acquiring mutex - solves deadlocks when we * re-enter the quota code and are already holding the mutex */ if (IS_NOQUOTA(inode)) return QUOTA_OK; for (cnt = 0; cnt < MAXQUOTAS; cnt++) 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); return QUOTA_OK; } spin_lock(&dq_data_lock); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (inode->i_dquot[cnt] == NODQUOT) continue; if (check_idq(inode->i_dquot[cnt], number, warntype+cnt) == NO_QUOTA) goto warn_put_all; } for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (inode->i_dquot[cnt] == NODQUOT) continue; dquot_incr_inodes(inode->i_dquot[cnt], number); } ret = QUOTA_OK; warn_put_all: spin_unlock(&dq_data_lock); if (ret == QUOTA_OK) /* Dirtify all the dquots - this can block when journalling */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) if (inode->i_dquot[cnt]) mark_dquot_dirty(inode->i_dquot[cnt]); flush_warnings(inode->i_dquot, warntype); up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); return ret; } /* * This operation can block, but only after everything is updated */ int dquot_free_space(struct inode *inode, qsize_t number) { unsigned int cnt; char warntype[MAXQUOTAS]; /* First test before acquiring mutex - solves deadlocks when we * re-enter the quota code and are already holding the mutex */ if (IS_NOQUOTA(inode)) { out_sub: inode_sub_bytes(inode, number); return QUOTA_OK; } down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); /* Now recheck reliably when holding dqptr_sem */ if (IS_NOQUOTA(inode)) { up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); goto out_sub; } spin_lock(&dq_data_lock); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (inode->i_dquot[cnt] == NODQUOT) continue; warntype[cnt] = info_bdq_free(inode->i_dquot[cnt], number); dquot_decr_space(inode->i_dquot[cnt], number); } inode_sub_bytes(inode, number); spin_unlock(&dq_data_lock); /* Dirtify all the dquots - this can block when journalling */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) if (inode->i_dquot[cnt]) mark_dquot_dirty(inode->i_dquot[cnt]); flush_warnings(inode->i_dquot, warntype); up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); return QUOTA_OK; } /* * This operation can block, but only after everything is updated */ int dquot_free_inode(const struct inode *inode, unsigned long number) { unsigned int cnt; char warntype[MAXQUOTAS]; /* First test before acquiring mutex - solves deadlocks when we * re-enter the quota code and are already holding the mutex */ if (IS_NOQUOTA(inode)) return QUOTA_OK; down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); /* Now recheck reliably when holding dqptr_sem */ if (IS_NOQUOTA(inode)) { up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); return QUOTA_OK; } spin_lock(&dq_data_lock); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (inode->i_dquot[cnt] == NODQUOT) continue; warntype[cnt] = info_idq_free(inode->i_dquot[cnt], number); dquot_decr_inodes(inode->i_dquot[cnt], number); } spin_unlock(&dq_data_lock); /* Dirtify all the dquots - this can block when journalling */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) if (inode->i_dquot[cnt]) mark_dquot_dirty(inode->i_dquot[cnt]); flush_warnings(inode->i_dquot, warntype); up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); return QUOTA_OK; } /* * Transfer the number of inode and blocks from one diskquota to an other. * * This operation can block, but only after everything is updated * A transaction must be started when entering this function. */ int dquot_transfer(struct inode *inode, struct iattr *iattr) { qsize_t space; struct dquot *transfer_from[MAXQUOTAS]; struct dquot *transfer_to[MAXQUOTAS]; int cnt, ret = NO_QUOTA, chuid = (iattr->ia_valid & ATTR_UID) && inode->i_uid != iattr->ia_uid, chgid = (iattr->ia_valid & ATTR_GID) && inode->i_gid != iattr->ia_gid; char warntype_to[MAXQUOTAS]; char warntype_from_inodes[MAXQUOTAS], warntype_from_space[MAXQUOTAS]; /* First test before acquiring mutex - solves deadlocks when we * re-enter the quota code and are already holding the mutex */ if (IS_NOQUOTA(inode)) return QUOTA_OK; /* Clear the arrays */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) { transfer_to[cnt] = transfer_from[cnt] = NODQUOT; warntype_to[cnt] = QUOTA_NL_NOWARN; } down_write(&sb_dqopt(inode->i_sb)->dqptr_sem); /* Now recheck reliably when holding dqptr_sem */ if (IS_NOQUOTA(inode)) { /* File without quota accounting? */ up_write(&sb_dqopt(inode->i_sb)->dqptr_sem); return QUOTA_OK; } /* First build the transfer_to list - here we can block on * reading/instantiating of dquots. We know that the transaction for * us was already started so we don't violate lock ranking here */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) { switch (cnt) { case USRQUOTA: if (!chuid) continue; transfer_to[cnt] = dqget(inode->i_sb, iattr->ia_uid, cnt); break; case GRPQUOTA: if (!chgid) continue; transfer_to[cnt] = dqget(inode->i_sb, iattr->ia_gid, cnt); break; } } spin_lock(&dq_data_lock); space = inode_get_bytes(inode); /* Build the transfer_from list and check the limits */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (transfer_to[cnt] == NODQUOT) continue; transfer_from[cnt] = inode->i_dquot[cnt]; if (check_idq(transfer_to[cnt], 1, warntype_to + cnt) == NO_QUOTA || check_bdq(transfer_to[cnt], space, 0, warntype_to + cnt) == NO_QUOTA) goto warn_put_all; } /* * Finally perform the needed transfer from transfer_from to transfer_to */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) { /* * Skip changes for same uid or gid or for turned off quota-type. */ if (transfer_to[cnt] == NODQUOT) continue; /* Due to IO error we might not have transfer_from[] structure */ if (transfer_from[cnt]) { warntype_from_inodes[cnt] = info_idq_free(transfer_from[cnt], 1); warntype_from_space[cnt] = info_bdq_free(transfer_from[cnt], space); dquot_decr_inodes(transfer_from[cnt], 1); dquot_decr_space(transfer_from[cnt], space); } dquot_incr_inodes(transfer_to[cnt], 1); dquot_incr_space(transfer_to[cnt], space); inode->i_dquot[cnt] = transfer_to[cnt]; } ret = QUOTA_OK; warn_put_all: spin_unlock(&dq_data_lock); /* Dirtify all the dquots - this can block when journalling */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (transfer_from[cnt]) mark_dquot_dirty(transfer_from[cnt]); if (transfer_to[cnt]) mark_dquot_dirty(transfer_to[cnt]); } flush_warnings(transfer_to, warntype_to); flush_warnings(transfer_from, warntype_from_inodes); flush_warnings(transfer_from, warntype_from_space); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (ret == QUOTA_OK && transfer_from[cnt] != NODQUOT) dqput(transfer_from[cnt]); if (ret == NO_QUOTA && transfer_to[cnt] != NODQUOT) dqput(transfer_to[cnt]); } up_write(&sb_dqopt(inode->i_sb)->dqptr_sem); return ret; } /* Wrapper for transferring ownership of an inode */ int vfs_dq_transfer(struct inode *inode, struct iattr *iattr) { if (sb_any_quota_enabled(inode->i_sb) && !IS_NOQUOTA(inode)) { vfs_dq_init(inode); if (inode->i_sb->dq_op->transfer(inode, iattr) == NO_QUOTA) return 1; } return 0; } /* * Write info of quota file to disk */ int dquot_commit_info(struct super_block *sb, int type) { int ret; struct quota_info *dqopt = sb_dqopt(sb); mutex_lock(&dqopt->dqio_mutex); ret = dqopt->ops[type]->write_file_info(sb, type); mutex_unlock(&dqopt->dqio_mutex); return ret; } /* * Definitions of diskquota operations. */ struct dquot_operations dquot_operations = { .initialize = dquot_initialize, .drop = dquot_drop, .alloc_space = dquot_alloc_space, .alloc_inode = dquot_alloc_inode, .free_space = dquot_free_space, .free_inode = dquot_free_inode, .transfer = dquot_transfer, .write_dquot = dquot_commit, .acquire_dquot = dquot_acquire, .release_dquot = dquot_release, .mark_dirty = dquot_mark_dquot_dirty, .write_info = dquot_commit_info }; static inline void set_enable_flags(struct quota_info *dqopt, int type) { switch (type) { case USRQUOTA: dqopt->flags |= DQUOT_USR_ENABLED; dqopt->flags &= ~DQUOT_USR_SUSPENDED; break; case GRPQUOTA: dqopt->flags |= DQUOT_GRP_ENABLED; dqopt->flags &= ~DQUOT_GRP_SUSPENDED; break; } } static inline void reset_enable_flags(struct quota_info *dqopt, int type, int remount) { switch (type) { case USRQUOTA: dqopt->flags &= ~DQUOT_USR_ENABLED; if (remount) dqopt->flags |= DQUOT_USR_SUSPENDED; else dqopt->flags &= ~DQUOT_USR_SUSPENDED; break; case GRPQUOTA: dqopt->flags &= ~DQUOT_GRP_ENABLED; if (remount) dqopt->flags |= DQUOT_GRP_SUSPENDED; else dqopt->flags &= ~DQUOT_GRP_SUSPENDED; break; } } /* * Turn quota off on a device. type == -1 ==> quotaoff for all types (umount) */ int vfs_quota_off(struct super_block *sb, int type, int remount) { int cnt, ret = 0; struct quota_info *dqopt = sb_dqopt(sb); struct inode *toputinode[MAXQUOTAS]; /* We need to serialize quota_off() for device */ mutex_lock(&dqopt->dqonoff_mutex); /* * Skip everything if there's nothing to do. We have to do this because * sometimes we are called when fill_super() failed and calling * sync_fs() in such cases does no good. */ if (!sb_any_quota_enabled(sb) && !sb_any_quota_suspended(sb)) { mutex_unlock(&dqopt->dqonoff_mutex); return 0; } for (cnt = 0; cnt < MAXQUOTAS; cnt++) { toputinode[cnt] = NULL; if (type != -1 && cnt != type) continue; /* If we keep inodes of quota files after remount and quotaoff * is called, drop kept inodes. */ if (!remount && sb_has_quota_suspended(sb, cnt)) { iput(dqopt->files[cnt]); dqopt->files[cnt] = NULL; reset_enable_flags(dqopt, cnt, 0); continue; } if (!sb_has_quota_enabled(sb, cnt)) continue; reset_enable_flags(dqopt, cnt, remount); /* Note: these are blocking operations */ drop_dquot_ref(sb, cnt); invalidate_dquots(sb, cnt); /* * Now all dquots should be invalidated, all writes done so we should be only * users of the info. No locks needed. */ if (info_dirty(&dqopt->info[cnt])) sb->dq_op->write_info(sb, cnt); if (dqopt->ops[cnt]->free_file_info) dqopt->ops[cnt]->free_file_info(sb, cnt); put_quota_format(dqopt->info[cnt].dqi_format); toputinode[cnt] = dqopt->files[cnt]; if (!remount) dqopt->files[cnt] = NULL; dqopt->info[cnt].dqi_flags = 0; dqopt->info[cnt].dqi_igrace = 0; dqopt->info[cnt].dqi_bgrace = 0; dqopt->ops[cnt] = NULL; } mutex_unlock(&dqopt->dqonoff_mutex); /* Sync the superblock so that buffers with quota data are written to * disk (and so userspace sees correct data afterwards). */ if (sb->s_op->sync_fs) sb->s_op->sync_fs(sb, 1); sync_blockdev(sb->s_bdev); /* Now the quota files are just ordinary files and we can set the * inode flags back. Moreover we discard the pagecache so that * userspace sees the writes we did bypassing the pagecache. We * must also discard the blockdev buffers so that we see the * changes done by userspace on the next quotaon() */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) if (toputinode[cnt]) { mutex_lock(&dqopt->dqonoff_mutex); /* If quota was reenabled in the meantime, we have * nothing to do */ if (!sb_has_quota_enabled(sb, cnt)) { mutex_lock_nested(&toputinode[cnt]->i_mutex, I_MUTEX_QUOTA); toputinode[cnt]->i_flags &= ~(S_IMMUTABLE | S_NOATIME | S_NOQUOTA); truncate_inode_pages(&toputinode[cnt]->i_data, 0); mutex_unlock(&toputinode[cnt]->i_mutex); mark_inode_dirty(toputinode[cnt]); } mutex_unlock(&dqopt->dqonoff_mutex); /* On remount RO, we keep the inode pointer so that we * can reenable quota on the subsequent remount RW. * But we have better not keep inode pointer when there * is pending delete on the quota file... */ if (!remount) iput(toputinode[cnt]); else if (!toputinode[cnt]->i_nlink) ret = -EBUSY; } if (sb->s_bdev) invalidate_bdev(sb->s_bdev); return ret; } /* * Turn quotas on on a device */ /* Helper function when we already have the inode */ static int vfs_quota_on_inode(struct inode *inode, int type, int format_id) { struct quota_format_type *fmt = find_quota_format(format_id); struct super_block *sb = inode->i_sb; struct quota_info *dqopt = sb_dqopt(sb); int error; int oldflags = -1; if (!fmt) return -ESRCH; if (!S_ISREG(inode->i_mode)) { error = -EACCES; goto out_fmt; } if (IS_RDONLY(inode)) { error = -EROFS; goto out_fmt; } if (!sb->s_op->quota_write || !sb->s_op->quota_read) { error = -EINVAL; goto out_fmt; } /* As we bypass the pagecache we must now flush the inode so that * we see all the changes from userspace... */ write_inode_now(inode, 1); /* And now flush the block cache so that kernel sees the changes */ invalidate_bdev(sb->s_bdev); mutex_lock(&inode->i_mutex); mutex_lock(&dqopt->dqonoff_mutex); if (sb_has_quota_enabled(sb, type) || sb_has_quota_suspended(sb, type)) { error = -EBUSY; goto out_lock; } /* We don't want quota and atime on quota files (deadlocks possible) * Also nobody should write to the file - we use special IO operations * which ignore the immutable bit. */ down_write(&dqopt->dqptr_sem); oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE | S_NOQUOTA); inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE; up_write(&dqopt->dqptr_sem); sb->dq_op->drop(inode); error = -EIO; dqopt->files[type] = igrab(inode); if (!dqopt->files[type]) goto out_lock; error = -EINVAL; if (!fmt->qf_ops->check_quota_file(sb, type)) goto out_file_init; dqopt->ops[type] = fmt->qf_ops; dqopt->info[type].dqi_format = fmt; dqopt->info[type].dqi_fmt_id = format_id; INIT_LIST_HEAD(&dqopt->info[type].dqi_dirty_list); mutex_lock(&dqopt->dqio_mutex); if ((error = dqopt->ops[type]->read_file_info(sb, type)) < 0) { mutex_unlock(&dqopt->dqio_mutex); goto out_file_init; } mutex_unlock(&dqopt->dqio_mutex); mutex_unlock(&inode->i_mutex); set_enable_flags(dqopt, type); add_dquot_ref(sb, type); mutex_unlock(&dqopt->dqonoff_mutex); return 0; out_file_init: dqopt->files[type] = NULL; iput(inode); out_lock: mutex_unlock(&dqopt->dqonoff_mutex); if (oldflags != -1) { down_write(&dqopt->dqptr_sem); /* Set the flags back (in the case of accidental quotaon() * on a wrong file we don't want to mess up the flags) */ inode->i_flags &= ~(S_NOATIME | S_NOQUOTA | S_IMMUTABLE); inode->i_flags |= oldflags; up_write(&dqopt->dqptr_sem); } mutex_unlock(&inode->i_mutex); out_fmt: put_quota_format(fmt); return error; } /* Reenable quotas on remount RW */ static int vfs_quota_on_remount(struct super_block *sb, int type) { struct quota_info *dqopt = sb_dqopt(sb); struct inode *inode; int ret; mutex_lock(&dqopt->dqonoff_mutex); if (!sb_has_quota_suspended(sb, type)) { mutex_unlock(&dqopt->dqonoff_mutex); return 0; } BUG_ON(sb_has_quota_enabled(sb, type)); inode = dqopt->files[type]; dqopt->files[type] = NULL; reset_enable_flags(dqopt, type, 0); mutex_unlock(&dqopt->dqonoff_mutex); ret = vfs_quota_on_inode(inode, type, dqopt->info[type].dqi_fmt_id); iput(inode); return ret; } int vfs_quota_on_path(struct super_block *sb, int type, int format_id, struct path *path) { int error = security_quota_on(path->dentry); if (error) return error; /* Quota file not on the same filesystem? */ if (path->mnt->mnt_sb != sb) error = -EXDEV; else error = vfs_quota_on_inode(path->dentry->d_inode, type, format_id); return error; } /* Actual function called from quotactl() */ int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path, int remount) { struct nameidata nd; int error; if (remount) return vfs_quota_on_remount(sb, type); error = path_lookup(path, LOOKUP_FOLLOW, &nd); if (!error) { error = vfs_quota_on_path(sb, type, format_id, &nd.path); path_put(&nd.path); } return error; } /* * This function is used when filesystem needs to initialize quotas * during mount time. */ int vfs_quota_on_mount(struct super_block *sb, char *qf_name, int format_id, int type) { struct dentry *dentry; int error; dentry = lookup_one_len(qf_name, sb->s_root, strlen(qf_name)); if (IS_ERR(dentry)) return PTR_ERR(dentry); if (!dentry->d_inode) { error = -ENOENT; goto out; } error = security_quota_on(dentry); if (!error) error = vfs_quota_on_inode(dentry->d_inode, type, format_id); out: dput(dentry); return error; } /* Wrapper to turn on quotas when remounting rw */ int vfs_dq_quota_on_remount(struct super_block *sb) { int cnt; int ret = 0, err; if (!sb->s_qcop || !sb->s_qcop->quota_on) return -ENOSYS; for (cnt = 0; cnt < MAXQUOTAS; cnt++) { err = sb->s_qcop->quota_on(sb, cnt, 0, NULL, 1); if (err < 0 && !ret) ret = err; } return ret; } /* Generic routine for getting common part of quota structure */ static void do_get_dqblk(struct dquot *dquot, struct if_dqblk *di) { struct mem_dqblk *dm = &dquot->dq_dqb; spin_lock(&dq_data_lock); di->dqb_bhardlimit = dm->dqb_bhardlimit; di->dqb_bsoftlimit = dm->dqb_bsoftlimit; di->dqb_curspace = dm->dqb_curspace; di->dqb_ihardlimit = dm->dqb_ihardlimit; di->dqb_isoftlimit = dm->dqb_isoftlimit; di->dqb_curinodes = dm->dqb_curinodes; di->dqb_btime = dm->dqb_btime; di->dqb_itime = dm->dqb_itime; di->dqb_valid = QIF_ALL; spin_unlock(&dq_data_lock); } int vfs_get_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *di) { struct dquot *dquot; mutex_lock(&sb_dqopt(sb)->dqonoff_mutex); if (!(dquot = dqget(sb, id, type))) { mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return -ESRCH; } do_get_dqblk(dquot, di); dqput(dquot); mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return 0; } /* Generic routine for setting common part of quota structure */ static int do_set_dqblk(struct dquot *dquot, struct if_dqblk *di) { struct mem_dqblk *dm = &dquot->dq_dqb; int check_blim = 0, check_ilim = 0; struct mem_dqinfo *dqi = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_type]; if ((di->dqb_valid & QIF_BLIMITS && (di->dqb_bhardlimit > dqi->dqi_maxblimit || di->dqb_bsoftlimit > dqi->dqi_maxblimit)) || (di->dqb_valid & QIF_ILIMITS && (di->dqb_ihardlimit > dqi->dqi_maxilimit || di->dqb_isoftlimit > dqi->dqi_maxilimit))) return -ERANGE; spin_lock(&dq_data_lock); if (di->dqb_valid & QIF_SPACE) { dm->dqb_curspace = di->dqb_curspace; check_blim = 1; } if (di->dqb_valid & QIF_BLIMITS) { dm->dqb_bsoftlimit = di->dqb_bsoftlimit; dm->dqb_bhardlimit = di->dqb_bhardlimit; check_blim = 1; } if (di->dqb_valid & QIF_INODES) { dm->dqb_curinodes = di->dqb_curinodes; check_ilim = 1; } if (di->dqb_valid & QIF_ILIMITS) { dm->dqb_isoftlimit = di->dqb_isoftlimit; dm->dqb_ihardlimit = di->dqb_ihardlimit; check_ilim = 1; } if (di->dqb_valid & QIF_BTIME) dm->dqb_btime = di->dqb_btime; if (di->dqb_valid & QIF_ITIME) dm->dqb_itime = di->dqb_itime; if (check_blim) { if (!dm->dqb_bsoftlimit || toqb(dm->dqb_curspace) < dm->dqb_bsoftlimit) { dm->dqb_btime = 0; clear_bit(DQ_BLKS_B, &dquot->dq_flags); } else if (!(di->dqb_valid & QIF_BTIME)) /* Set grace only if user hasn't provided his own... */ dm->dqb_btime = get_seconds() + dqi->dqi_bgrace; } if (check_ilim) { if (!dm->dqb_isoftlimit || dm->dqb_curinodes < dm->dqb_isoftlimit) { dm->dqb_itime = 0; clear_bit(DQ_INODES_B, &dquot->dq_flags); } else if (!(di->dqb_valid & QIF_ITIME)) /* Set grace only if user hasn't provided his own... */ dm->dqb_itime = get_seconds() + dqi->dqi_igrace; } if (dm->dqb_bhardlimit || dm->dqb_bsoftlimit || dm->dqb_ihardlimit || dm->dqb_isoftlimit) clear_bit(DQ_FAKE_B, &dquot->dq_flags); else set_bit(DQ_FAKE_B, &dquot->dq_flags); spin_unlock(&dq_data_lock); mark_dquot_dirty(dquot); return 0; } int vfs_set_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *di) { struct dquot *dquot; int rc; mutex_lock(&sb_dqopt(sb)->dqonoff_mutex); if (!(dquot = dqget(sb, id, type))) { mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return -ESRCH; } rc = do_set_dqblk(dquot, di); dqput(dquot); mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return rc; } /* Generic routine for getting common part of quota file information */ int vfs_get_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii) { struct mem_dqinfo *mi; mutex_lock(&sb_dqopt(sb)->dqonoff_mutex); if (!sb_has_quota_enabled(sb, type)) { mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return -ESRCH; } mi = sb_dqopt(sb)->info + type; spin_lock(&dq_data_lock); ii->dqi_bgrace = mi->dqi_bgrace; ii->dqi_igrace = mi->dqi_igrace; ii->dqi_flags = mi->dqi_flags & DQF_MASK; ii->dqi_valid = IIF_ALL; spin_unlock(&dq_data_lock); mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return 0; } /* Generic routine for setting common part of quota file information */ int vfs_set_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii) { struct mem_dqinfo *mi; mutex_lock(&sb_dqopt(sb)->dqonoff_mutex); if (!sb_has_quota_enabled(sb, type)) { mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return -ESRCH; } mi = sb_dqopt(sb)->info + type; spin_lock(&dq_data_lock); if (ii->dqi_valid & IIF_BGRACE) mi->dqi_bgrace = ii->dqi_bgrace; if (ii->dqi_valid & IIF_IGRACE) mi->dqi_igrace = ii->dqi_igrace; if (ii->dqi_valid & IIF_FLAGS) mi->dqi_flags = (mi->dqi_flags & ~DQF_MASK) | (ii->dqi_flags & DQF_MASK); spin_unlock(&dq_data_lock); mark_info_dirty(sb, type); /* Force write to disk */ sb->dq_op->write_info(sb, type); mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); return 0; } struct quotactl_ops vfs_quotactl_ops = { .quota_on = vfs_quota_on, .quota_off = vfs_quota_off, .quota_sync = vfs_quota_sync, .get_info = vfs_get_dqinfo, .set_info = vfs_set_dqinfo, .get_dqblk = vfs_get_dqblk, .set_dqblk = vfs_set_dqblk }; static ctl_table fs_dqstats_table[] = { { .ctl_name = FS_DQ_LOOKUPS, .procname = "lookups", .data = &dqstats.lookups, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, { .ctl_name = FS_DQ_DROPS, .procname = "drops", .data = &dqstats.drops, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, { .ctl_name = FS_DQ_READS, .procname = "reads", .data = &dqstats.reads, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, { .ctl_name = FS_DQ_WRITES, .procname = "writes", .data = &dqstats.writes, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, { .ctl_name = FS_DQ_CACHE_HITS, .procname = "cache_hits", .data = &dqstats.cache_hits, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, { .ctl_name = FS_DQ_ALLOCATED, .procname = "allocated_dquots", .data = &dqstats.allocated_dquots, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, { .ctl_name = FS_DQ_FREE, .procname = "free_dquots", .data = &dqstats.free_dquots, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, { .ctl_name = FS_DQ_SYNCS, .procname = "syncs", .data = &dqstats.syncs, .maxlen = sizeof(int), .mode = 0444, .proc_handler = &proc_dointvec, }, #ifdef CONFIG_PRINT_QUOTA_WARNING { .ctl_name = FS_DQ_WARNINGS, .procname = "warnings", .data = &flag_print_warnings, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec, }, #endif { .ctl_name = 0 }, }; static ctl_table fs_table[] = { { .ctl_name = FS_DQSTATS, .procname = "quota", .mode = 0555, .child = fs_dqstats_table, }, { .ctl_name = 0 }, }; static ctl_table sys_table[] = { { .ctl_name = CTL_FS, .procname = "fs", .mode = 0555, .child = fs_table, }, { .ctl_name = 0 }, }; static int __init dquot_init(void) { int i; unsigned long nr_hash, order; printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__); register_sysctl_table(sys_table); dquot_cachep = kmem_cache_create("dquot", sizeof(struct dquot), sizeof(unsigned long) * 4, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| SLAB_MEM_SPREAD|SLAB_PANIC), NULL); order = 0; dquot_hash = (struct hlist_head *)__get_free_pages(GFP_ATOMIC, order); if (!dquot_hash) panic("Cannot create dquot hash table"); /* Find power-of-two hlist_heads which can fit into allocation */ nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head); dq_hash_bits = 0; do { dq_hash_bits++; } while (nr_hash >> dq_hash_bits); dq_hash_bits--; nr_hash = 1UL << dq_hash_bits; dq_hash_mask = nr_hash - 1; for (i = 0; i < nr_hash; i++) INIT_HLIST_HEAD(dquot_hash + i); printk("Dquot-cache hash table entries: %ld (order %ld, %ld bytes)\n", nr_hash, order, (PAGE_SIZE << order)); 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); EXPORT_SYMBOL(register_quota_format); EXPORT_SYMBOL(unregister_quota_format); EXPORT_SYMBOL(dqstats); EXPORT_SYMBOL(dq_data_lock); EXPORT_SYMBOL(vfs_quota_on); EXPORT_SYMBOL(vfs_quota_on_path); EXPORT_SYMBOL(vfs_quota_on_mount); EXPORT_SYMBOL(vfs_quota_off); EXPORT_SYMBOL(vfs_quota_sync); EXPORT_SYMBOL(vfs_get_dqinfo); EXPORT_SYMBOL(vfs_set_dqinfo); EXPORT_SYMBOL(vfs_get_dqblk); EXPORT_SYMBOL(vfs_set_dqblk); EXPORT_SYMBOL(dquot_commit); EXPORT_SYMBOL(dquot_commit_info); EXPORT_SYMBOL(dquot_acquire); EXPORT_SYMBOL(dquot_release); EXPORT_SYMBOL(dquot_mark_dquot_dirty); EXPORT_SYMBOL(dquot_initialize); EXPORT_SYMBOL(dquot_drop); EXPORT_SYMBOL(vfs_dq_drop); EXPORT_SYMBOL(dquot_alloc_space); EXPORT_SYMBOL(dquot_alloc_inode); EXPORT_SYMBOL(dquot_free_space); EXPORT_SYMBOL(dquot_free_inode); EXPORT_SYMBOL(dquot_transfer); EXPORT_SYMBOL(vfs_dq_transfer); EXPORT_SYMBOL(vfs_dq_quota_on_remount);