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@@ -22,23 +22,15 @@
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#include <linux/module.h>
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#include <linux/slab.h>
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-#include <linux/init.h>
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-#include <linux/smp_lock.h>
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#include <linux/acct.h>
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#include <linux/blkdev.h>
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#include <linux/quotaops.h>
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-#include <linux/namei.h>
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#include <linux/mount.h>
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#include <linux/security.h>
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-#include <linux/syscalls.h>
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-#include <linux/vfs.h>
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#include <linux/writeback.h> /* for the emergency remount stuff */
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#include <linux/idr.h>
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-#include <linux/kobject.h>
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#include <linux/mutex.h>
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-#include <linux/file.h>
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#include <linux/backing-dev.h>
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-#include <asm/uaccess.h>
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#include "internal.h"
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@@ -93,9 +85,10 @@ static struct super_block *alloc_super(struct file_system_type *type)
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* subclass.
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*/
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down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
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- s->s_count = S_BIAS;
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+ s->s_count = 1;
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atomic_set(&s->s_active, 1);
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mutex_init(&s->s_vfs_rename_mutex);
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+ lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
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mutex_init(&s->s_dquot.dqio_mutex);
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mutex_init(&s->s_dquot.dqonoff_mutex);
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init_rwsem(&s->s_dquot.dqptr_sem);
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@@ -127,39 +120,14 @@ static inline void destroy_super(struct super_block *s)
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/* Superblock refcounting */
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/*
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- * Drop a superblock's refcount. Returns non-zero if the superblock was
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- * destroyed. The caller must hold sb_lock.
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+ * Drop a superblock's refcount. The caller must hold sb_lock.
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*/
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-static int __put_super(struct super_block *sb)
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+void __put_super(struct super_block *sb)
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{
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- int ret = 0;
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-
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if (!--sb->s_count) {
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+ list_del_init(&sb->s_list);
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destroy_super(sb);
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- ret = 1;
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}
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- return ret;
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-}
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-
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-/*
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- * Drop a superblock's refcount.
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- * Returns non-zero if the superblock is about to be destroyed and
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- * at least is already removed from super_blocks list, so if we are
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- * making a loop through super blocks then we need to restart.
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- * The caller must hold sb_lock.
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- */
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-int __put_super_and_need_restart(struct super_block *sb)
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-{
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- /* check for race with generic_shutdown_super() */
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- if (list_empty(&sb->s_list)) {
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- /* super block is removed, need to restart... */
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- __put_super(sb);
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- return 1;
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- }
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- /* can't be the last, since s_list is still in use */
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- sb->s_count--;
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- BUG_ON(sb->s_count == 0);
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- return 0;
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}
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/**
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@@ -178,57 +146,48 @@ void put_super(struct super_block *sb)
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/**
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- * deactivate_super - drop an active reference to superblock
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+ * deactivate_locked_super - drop an active reference to superblock
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* @s: superblock to deactivate
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*
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- * Drops an active reference to superblock, acquiring a temprory one if
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- * there is no active references left. In that case we lock superblock,
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+ * Drops an active reference to superblock, converting it into a temprory
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+ * one if there is no other active references left. In that case we
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* tell fs driver to shut it down and drop the temporary reference we
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* had just acquired.
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+ *
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+ * Caller holds exclusive lock on superblock; that lock is released.
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*/
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-void deactivate_super(struct super_block *s)
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+void deactivate_locked_super(struct super_block *s)
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{
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struct file_system_type *fs = s->s_type;
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- if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
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- s->s_count -= S_BIAS-1;
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- spin_unlock(&sb_lock);
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+ if (atomic_dec_and_test(&s->s_active)) {
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vfs_dq_off(s, 0);
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- down_write(&s->s_umount);
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fs->kill_sb(s);
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put_filesystem(fs);
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put_super(s);
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+ } else {
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+ up_write(&s->s_umount);
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}
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}
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-EXPORT_SYMBOL(deactivate_super);
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+EXPORT_SYMBOL(deactivate_locked_super);
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/**
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- * deactivate_locked_super - drop an active reference to superblock
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+ * deactivate_super - drop an active reference to superblock
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* @s: superblock to deactivate
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*
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- * Equivalent of up_write(&s->s_umount); deactivate_super(s);, except that
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- * it does not unlock it until it's all over. As the result, it's safe to
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- * use to dispose of new superblock on ->get_sb() failure exits - nobody
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- * will see the sucker until it's all over. Equivalent using up_write +
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- * deactivate_super is safe for that purpose only if superblock is either
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- * safe to use or has NULL ->s_root when we unlock.
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+ * Variant of deactivate_locked_super(), except that superblock is *not*
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+ * locked by caller. If we are going to drop the final active reference,
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+ * lock will be acquired prior to that.
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*/
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-void deactivate_locked_super(struct super_block *s)
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+void deactivate_super(struct super_block *s)
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{
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- struct file_system_type *fs = s->s_type;
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- if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
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- s->s_count -= S_BIAS-1;
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- spin_unlock(&sb_lock);
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- vfs_dq_off(s, 0);
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- fs->kill_sb(s);
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- put_filesystem(fs);
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- put_super(s);
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- } else {
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- up_write(&s->s_umount);
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+ if (!atomic_add_unless(&s->s_active, -1, 1)) {
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+ down_write(&s->s_umount);
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+ deactivate_locked_super(s);
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}
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}
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-EXPORT_SYMBOL(deactivate_locked_super);
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+EXPORT_SYMBOL(deactivate_super);
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/**
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* grab_super - acquire an active reference
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@@ -243,22 +202,17 @@ EXPORT_SYMBOL(deactivate_locked_super);
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*/
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static int grab_super(struct super_block *s) __releases(sb_lock)
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{
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+ if (atomic_inc_not_zero(&s->s_active)) {
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+ spin_unlock(&sb_lock);
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+ return 1;
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+ }
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+ /* it's going away */
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s->s_count++;
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spin_unlock(&sb_lock);
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+ /* wait for it to die */
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down_write(&s->s_umount);
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- if (s->s_root) {
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- spin_lock(&sb_lock);
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- if (s->s_count > S_BIAS) {
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- atomic_inc(&s->s_active);
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- s->s_count--;
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- spin_unlock(&sb_lock);
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- return 1;
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- }
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- spin_unlock(&sb_lock);
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- }
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up_write(&s->s_umount);
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put_super(s);
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- yield();
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return 0;
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}
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@@ -321,8 +275,7 @@ void generic_shutdown_super(struct super_block *sb)
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}
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spin_lock(&sb_lock);
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/* should be initialized for __put_super_and_need_restart() */
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- list_del_init(&sb->s_list);
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- list_del(&sb->s_instances);
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+ list_del_init(&sb->s_instances);
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spin_unlock(&sb_lock);
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up_write(&sb->s_umount);
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}
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@@ -357,6 +310,7 @@ retry:
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up_write(&s->s_umount);
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destroy_super(s);
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}
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+ down_write(&old->s_umount);
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return old;
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}
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}
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@@ -408,11 +362,12 @@ EXPORT_SYMBOL(drop_super);
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*/
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void sync_supers(void)
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{
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- struct super_block *sb;
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+ struct super_block *sb, *n;
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spin_lock(&sb_lock);
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-restart:
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- list_for_each_entry(sb, &super_blocks, s_list) {
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+ list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
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+ if (list_empty(&sb->s_instances))
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+ continue;
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if (sb->s_op->write_super && sb->s_dirt) {
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sb->s_count++;
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spin_unlock(&sb_lock);
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@@ -423,13 +378,42 @@ restart:
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up_read(&sb->s_umount);
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spin_lock(&sb_lock);
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- if (__put_super_and_need_restart(sb))
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- goto restart;
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+ __put_super(sb);
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}
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}
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spin_unlock(&sb_lock);
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}
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+/**
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+ * iterate_supers - call function for all active superblocks
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+ * @f: function to call
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+ * @arg: argument to pass to it
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+ *
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+ * Scans the superblock list and calls given function, passing it
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+ * locked superblock and given argument.
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+ */
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+void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
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+{
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+ struct super_block *sb, *n;
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+
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+ spin_lock(&sb_lock);
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+ list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
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+ if (list_empty(&sb->s_instances))
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+ continue;
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+ sb->s_count++;
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+ spin_unlock(&sb_lock);
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+
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+ down_read(&sb->s_umount);
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+ if (sb->s_root)
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+ f(sb, arg);
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+ up_read(&sb->s_umount);
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+
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+ spin_lock(&sb_lock);
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+ __put_super(sb);
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+ }
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+ spin_unlock(&sb_lock);
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+}
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+
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/**
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* get_super - get the superblock of a device
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* @bdev: device to get the superblock for
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@@ -438,7 +422,7 @@ restart:
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* mounted on the device given. %NULL is returned if no match is found.
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*/
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-struct super_block * get_super(struct block_device *bdev)
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+struct super_block *get_super(struct block_device *bdev)
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{
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struct super_block *sb;
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@@ -448,17 +432,20 @@ struct super_block * get_super(struct block_device *bdev)
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spin_lock(&sb_lock);
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rescan:
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list_for_each_entry(sb, &super_blocks, s_list) {
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+ if (list_empty(&sb->s_instances))
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+ continue;
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if (sb->s_bdev == bdev) {
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sb->s_count++;
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spin_unlock(&sb_lock);
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down_read(&sb->s_umount);
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+ /* still alive? */
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if (sb->s_root)
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return sb;
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up_read(&sb->s_umount);
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- /* restart only when sb is no longer on the list */
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+ /* nope, got unmounted */
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spin_lock(&sb_lock);
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- if (__put_super_and_need_restart(sb))
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- goto rescan;
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+ __put_super(sb);
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+ goto rescan;
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}
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}
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spin_unlock(&sb_lock);
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@@ -473,7 +460,7 @@ EXPORT_SYMBOL(get_super);
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*
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* Scans the superblock list and finds the superblock of the file system
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* mounted on the device given. Returns the superblock with an active
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- * reference and s_umount held exclusively or %NULL if none was found.
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+ * reference or %NULL if none was found.
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*/
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struct super_block *get_active_super(struct block_device *bdev)
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{
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@@ -482,81 +469,49 @@ struct super_block *get_active_super(struct block_device *bdev)
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if (!bdev)
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return NULL;
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+restart:
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spin_lock(&sb_lock);
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list_for_each_entry(sb, &super_blocks, s_list) {
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- if (sb->s_bdev != bdev)
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+ if (list_empty(&sb->s_instances))
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continue;
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-
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- sb->s_count++;
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- spin_unlock(&sb_lock);
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- down_write(&sb->s_umount);
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- if (sb->s_root) {
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- spin_lock(&sb_lock);
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- if (sb->s_count > S_BIAS) {
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- atomic_inc(&sb->s_active);
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- sb->s_count--;
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- spin_unlock(&sb_lock);
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+ if (sb->s_bdev == bdev) {
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+ if (grab_super(sb)) /* drops sb_lock */
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return sb;
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- }
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- spin_unlock(&sb_lock);
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+ else
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+ goto restart;
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}
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- up_write(&sb->s_umount);
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- put_super(sb);
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- yield();
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- spin_lock(&sb_lock);
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}
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spin_unlock(&sb_lock);
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return NULL;
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}
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-struct super_block * user_get_super(dev_t dev)
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+struct super_block *user_get_super(dev_t dev)
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{
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struct super_block *sb;
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spin_lock(&sb_lock);
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rescan:
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list_for_each_entry(sb, &super_blocks, s_list) {
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+ if (list_empty(&sb->s_instances))
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+ continue;
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if (sb->s_dev == dev) {
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sb->s_count++;
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spin_unlock(&sb_lock);
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down_read(&sb->s_umount);
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+ /* still alive? */
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if (sb->s_root)
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return sb;
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up_read(&sb->s_umount);
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- /* restart only when sb is no longer on the list */
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+ /* nope, got unmounted */
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spin_lock(&sb_lock);
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- if (__put_super_and_need_restart(sb))
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- goto rescan;
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+ __put_super(sb);
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+ goto rescan;
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}
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}
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spin_unlock(&sb_lock);
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return NULL;
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}
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-SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
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-{
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- struct super_block *s;
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- struct ustat tmp;
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- struct kstatfs sbuf;
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- int err = -EINVAL;
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-
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- s = user_get_super(new_decode_dev(dev));
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- if (s == NULL)
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- goto out;
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- err = vfs_statfs(s->s_root, &sbuf);
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- drop_super(s);
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- if (err)
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- goto out;
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-
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- memset(&tmp,0,sizeof(struct ustat));
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- tmp.f_tfree = sbuf.f_bfree;
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- tmp.f_tinode = sbuf.f_ffree;
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-
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- err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
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-out:
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- return err;
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-}
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-
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/**
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* do_remount_sb - asks filesystem to change mount options.
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* @sb: superblock in question
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@@ -622,24 +577,24 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
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static void do_emergency_remount(struct work_struct *work)
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{
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- struct super_block *sb;
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+ struct super_block *sb, *n;
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spin_lock(&sb_lock);
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- list_for_each_entry(sb, &super_blocks, s_list) {
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+ list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
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+ if (list_empty(&sb->s_instances))
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+ continue;
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sb->s_count++;
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spin_unlock(&sb_lock);
|
|
|
down_write(&sb->s_umount);
|
|
|
if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
|
|
|
/*
|
|
|
- * ->remount_fs needs lock_kernel().
|
|
|
- *
|
|
|
* What lock protects sb->s_flags??
|
|
|
*/
|
|
|
do_remount_sb(sb, MS_RDONLY, NULL, 1);
|
|
|
}
|
|
|
up_write(&sb->s_umount);
|
|
|
- put_super(sb);
|
|
|
spin_lock(&sb_lock);
|
|
|
+ __put_super(sb);
|
|
|
}
|
|
|
spin_unlock(&sb_lock);
|
|
|
kfree(work);
|
|
@@ -990,6 +945,96 @@ out:
|
|
|
|
|
|
EXPORT_SYMBOL_GPL(vfs_kern_mount);
|
|
|
|
|
|
+/**
|
|
|
+ * freeze_super -- lock the filesystem and force it into a consistent state
|
|
|
+ * @super: the super to lock
|
|
|
+ *
|
|
|
+ * Syncs the super to make sure the filesystem is consistent and calls the fs's
|
|
|
+ * freeze_fs. Subsequent calls to this without first thawing the fs will return
|
|
|
+ * -EBUSY.
|
|
|
+ */
|
|
|
+int freeze_super(struct super_block *sb)
|
|
|
+{
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ atomic_inc(&sb->s_active);
|
|
|
+ down_write(&sb->s_umount);
|
|
|
+ if (sb->s_frozen) {
|
|
|
+ deactivate_locked_super(sb);
|
|
|
+ return -EBUSY;
|
|
|
+ }
|
|
|
+
|
|
|
+ if (sb->s_flags & MS_RDONLY) {
|
|
|
+ sb->s_frozen = SB_FREEZE_TRANS;
|
|
|
+ smp_wmb();
|
|
|
+ up_write(&sb->s_umount);
|
|
|
+ return 0;
|
|
|
+ }
|
|
|
+
|
|
|
+ sb->s_frozen = SB_FREEZE_WRITE;
|
|
|
+ smp_wmb();
|
|
|
+
|
|
|
+ sync_filesystem(sb);
|
|
|
+
|
|
|
+ sb->s_frozen = SB_FREEZE_TRANS;
|
|
|
+ smp_wmb();
|
|
|
+
|
|
|
+ sync_blockdev(sb->s_bdev);
|
|
|
+ if (sb->s_op->freeze_fs) {
|
|
|
+ ret = sb->s_op->freeze_fs(sb);
|
|
|
+ if (ret) {
|
|
|
+ printk(KERN_ERR
|
|
|
+ "VFS:Filesystem freeze failed\n");
|
|
|
+ sb->s_frozen = SB_UNFROZEN;
|
|
|
+ deactivate_locked_super(sb);
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+ }
|
|
|
+ up_write(&sb->s_umount);
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL(freeze_super);
|
|
|
+
|
|
|
+/**
|
|
|
+ * thaw_super -- unlock filesystem
|
|
|
+ * @sb: the super to thaw
|
|
|
+ *
|
|
|
+ * Unlocks the filesystem and marks it writeable again after freeze_super().
|
|
|
+ */
|
|
|
+int thaw_super(struct super_block *sb)
|
|
|
+{
|
|
|
+ int error;
|
|
|
+
|
|
|
+ down_write(&sb->s_umount);
|
|
|
+ if (sb->s_frozen == SB_UNFROZEN) {
|
|
|
+ up_write(&sb->s_umount);
|
|
|
+ return -EINVAL;
|
|
|
+ }
|
|
|
+
|
|
|
+ if (sb->s_flags & MS_RDONLY)
|
|
|
+ goto out;
|
|
|
+
|
|
|
+ if (sb->s_op->unfreeze_fs) {
|
|
|
+ error = sb->s_op->unfreeze_fs(sb);
|
|
|
+ if (error) {
|
|
|
+ printk(KERN_ERR
|
|
|
+ "VFS:Filesystem thaw failed\n");
|
|
|
+ sb->s_frozen = SB_FREEZE_TRANS;
|
|
|
+ up_write(&sb->s_umount);
|
|
|
+ return error;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+out:
|
|
|
+ sb->s_frozen = SB_UNFROZEN;
|
|
|
+ smp_wmb();
|
|
|
+ wake_up(&sb->s_wait_unfrozen);
|
|
|
+ deactivate_locked_super(sb);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL(thaw_super);
|
|
|
+
|
|
|
static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
|
|
|
{
|
|
|
int err;
|