[PATCH] Fix of quota deadlock on pagelock: quota core

The four patches in this series fix deadlocks with quotas of pagelock (the
problem was lock inversion on PageLock and transaction start - quota code
needed to first start a transaction and then write the data which subsequently
needed acquisition of PageLock while the standard ordering - PageLock first
and transaction start later - was used e.g.  by pdflush).  They implement a
new way of quota access to disk: Every filesystem that would like to implement
quotas now has to provide quota_read() and quota_write() functions.  These
functions must obey quota lock ordering (in particular they should not take
PageLock inside a transaction).

The first patch implements the changes in the quota core, the other three
patches implement needed functions in ext2, ext3 and reiserfs.  The patch for
reiserfs also fixes several other lock inversion problems (similar as ext3
had) and implements the journaled quota functionality (which comes almost for
free after the locking fixes...).

The quota core patch makes quota support in other filesystems (except XFS
which implements everything on its own ;)) unfunctional (quotaon() will refuse
to turn on quotas on them).  When the patches get reasonable wide testing and
it will seem that no major changes will be needed I can make fixes also for
the other filesystems (JFS, UDF, UFS).

This patch:

The patch implements the new way of quota io in the quota core.  Every
filesystem wanting to support quotas has to provide functions quota_read()
and quota_write() obeying quota locking rules.  As the writes and reads
bypass the pagecache there is some ugly stuff ensuring that userspace can
see all the data after quotaoff() (or Q_SYNC quotactl).  In future I plan
to make quota files inaccessible from userspace (with the exception of
quotacheck(8) which will take care about the cache flushing and such stuff
itself) so that this synchronization stuff can be removed...

The rewrite of the quota core. Quota uses the filesystem read() and write()
functions no more to avoid possible deadlocks on PageLock. From now on every
filesystem supporting quotas must provide functions quota_read() and
quota_write() which obey the quota locking rules (e.g. they cannot acquire the
PageLock).

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 237 insertions, 260 deletions

diff --git a/fs/dquot.c b/fs/dquot.c
index dad9d59edf6914..fd9cb2a75e64b8 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -49,7 +49,7 @@
  *		New SMP locking.
  *		Jan Kara, <jack@suse.cz>, 10/2002
  *
- *		Added journalled quota support
+ *		Added journalled quota support, fix lock inversion problems
  *		Jan Kara, <jack@suse.cz>, 2003,2004
  *
  * (C) Copyright 1994 - 1997 Marco van Wieringen 
@@ -75,7 +75,8 @@
 #include <linux/proc_fs.h>
 #include <linux/security.h>
 #include <linux/kmod.h>
-#include <linux/pagemap.h>
+#include <linux/namei.h>
+#include <linux/buffer_head.h>
 
 #include <asm/uaccess.h>
 
@@ -114,7 +115,7 @@
  * 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 following:
+ * Lock ordering (including related VFS locks) is the following:
  *   i_sem > dqonoff_sem > iprune_sem > journal_lock > dqptr_sem >
  *   > dquot->dq_lock > dqio_sem
  * i_sem on quota files is special (it's below dqio_sem)
@@ -183,8 +184,7 @@ static void put_quota_format(struct quota_format_type *fmt)
  * 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 the sync and invalidate operations, which must look
- * at every dquot.
+ * 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
@@ -1314,10 +1314,12 @@ int vfs_quota_off(struct super_block *sb, int type)
 {
 	int cnt;
 	struct quota_info *dqopt = sb_dqopt(sb);
+	struct inode *toput[MAXQUOTAS];
 
 	/* We need to serialize quota_off() for device */
 	down(&dqopt->dqonoff_sem);
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
+		toput[cnt] = NULL;
 		if (type != -1 && cnt != type)
 			continue;
 		if (!sb_has_quota_enabled(sb, cnt))
@@ -1337,7 +1339,7 @@ int vfs_quota_off(struct super_block *sb, int type)
 			dqopt->ops[cnt]->free_file_info(sb, cnt);
 		put_quota_format(dqopt->info[cnt].dqi_format);
 
-		fput(dqopt->files[cnt]);
+		toput[cnt] = dqopt->files[cnt];
 		dqopt->files[cnt] = NULL;
 		dqopt->info[cnt].dqi_flags = 0;
 		dqopt->info[cnt].dqi_igrace = 0;
@@ -1345,6 +1347,27 @@ int vfs_quota_off(struct super_block *sb, int type)
 		dqopt->ops[cnt] = NULL;
 	}
 	up(&dqopt->dqonoff_sem);
+	/* 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 (toput[cnt]) {
+			down(&toput[cnt]->i_sem);
+			toput[cnt]->i_flags &= ~(S_IMMUTABLE | S_NOATIME | S_NOQUOTA);
+			truncate_inode_pages(&toput[cnt]->i_data, 0);
+			up(&toput[cnt]->i_sem);
+			mark_inode_dirty(toput[cnt]);
+			iput(toput[cnt]);
+		}
+	if (sb->s_bdev)
+		invalidate_bdev(sb->s_bdev, 0);
 	return 0;
 }
 
@@ -1352,68 +1375,56 @@ int vfs_quota_off(struct super_block *sb, int type)
  *	Turn quotas on on a device
  */
 
-/* Helper function when we already have file open */
-static int vfs_quota_on_file(struct file *f, int type, int format_id)
+/* 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 inode *inode;
-	struct super_block *sb = f->f_dentry->d_sb;
+	struct super_block *sb = inode->i_sb;
 	struct quota_info *dqopt = sb_dqopt(sb);
-	struct dquot *to_drop[MAXQUOTAS];
-	int error, cnt;
-	unsigned int oldflags = -1;
+	int error;
+	int oldflags = -1;
 
 	if (!fmt)
 		return -ESRCH;
-	error = -EIO;
-	if (!f->f_op || !f->f_op->read || !f->f_op->write)
+	if (!S_ISREG(inode->i_mode)) {
+		error = -EACCES;
 		goto out_fmt;
-	inode = f->f_dentry->d_inode;
-	error = -EACCES;
-	if (!S_ISREG(inode->i_mode))
+	}
+	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, 0);
 	down(&inode->i_sem);
 	down(&dqopt->dqonoff_sem);
 	if (sb_has_quota_enabled(sb, type)) {
-		up(&inode->i_sem);
 		error = -EBUSY;
 		goto out_lock;
 	}
 	/* We don't want quota and atime on quota files (deadlocks possible)
-	 * We also need to set GFP mask differently because we cannot recurse
-	 * into filesystem when allocating page for quota inode */
+	 * 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_NOQUOTA);
-	inode->i_flags |= S_NOQUOTA | S_NOATIME;
+	oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE | S_NOQUOTA);
+	inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE;
 	up_write(&dqopt->dqptr_sem);
-	up(&inode->i_sem);
 
-	dqopt->files[type] = f;
+	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;
-	/*
-	 * We write to quota files deep within filesystem code.  We don't want
-	 * the VFS to reenter filesystem code when it tries to allocate a
-	 * pagecache page for the quota file write.  So clear __GFP_FS in
-	 * the quota file's allocation flags.
-	 */
-	mapping_set_gfp_mask(inode->i_mapping,
-		mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
-
-	down_write(&dqopt->dqptr_sem);
-	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
-		to_drop[cnt] = inode->i_dquot[cnt];
-		inode->i_dquot[cnt] = NODQUOT;
-	}
-	up_write(&dqopt->dqptr_sem);
-	/* We must put dquots outside of dqptr_sem because we may need to
-	 * start transaction for dquot_release() */
-	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
-		if (to_drop[cnt])
-			dqput(to_drop[cnt]);
-	}
 
 	dqopt->ops[type] = fmt->qf_ops;
 	dqopt->info[type].dqi_format = fmt;
@@ -1424,6 +1435,7 @@ static int vfs_quota_on_file(struct file *f, int type, int format_id)
 		goto out_file_init;
 	}
 	up(&dqopt->dqio_sem);
+	up(&inode->i_sem);
 	set_enable_flags(dqopt, type);
 
 	add_dquot_ref(sb, type);
@@ -1433,19 +1445,18 @@ static int vfs_quota_on_file(struct file *f, int type, int format_id)
 
 out_file_init:
 	dqopt->files[type] = NULL;
+	iput(inode);
 out_lock:
 	up(&dqopt->dqonoff_sem);
 	if (oldflags != -1) {
-		down(&inode->i_sem);
 		down_write(&dqopt->dqptr_sem);
-		/* Reset the NOATIME flag back. I know it could change in the
-		 * mean time but playing with NOATIME flags on a quota file is
-		 * never a good idea */
-		inode->i_flags &= ~(S_NOATIME | S_NOQUOTA);
+		/* 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);
-		up(&inode->i_sem);
 	}
+	up(&inode->i_sem);
 out_fmt:
 	put_quota_format(fmt);
 
@@ -1455,47 +1466,37 @@ out_fmt:
 /* Actual function called from quotactl() */
 int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path)
 {
-	struct file *f;
+	struct nameidata nd;
 	int error;
 
-	f = filp_open(path, O_RDWR, 0600);
-	if (IS_ERR(f))
-		return PTR_ERR(f);
-	error = security_quota_on(f);
+	error = path_lookup(path, LOOKUP_FOLLOW, &nd);
+	if (error < 0)
+		return error;
+	error = security_quota_on(nd.dentry);
 	if (error)
-		goto out_f;
-	error = vfs_quota_on_file(f, type, format_id);
-	if (!error)
-		return 0;
-out_f:
-	filp_close(f, NULL);
+		goto out_path;
+	/* Quota file not on the same filesystem? */
+	if (nd.mnt->mnt_sb != sb)
+		error = -EXDEV;
+	else
+		error = vfs_quota_on_inode(nd.dentry->d_inode, type, format_id);
+out_path:
+	path_release(&nd);
 	return error;
 }
 
 /*
- * Function used by filesystems when filp_open() would fail (filesystem is
- * being mounted now). We will use a private file structure. Caller is
- * responsible that it's IO functions won't need vfsmnt structure or
- * some dentry tricks...
+ * This function is used when filesystem needs to initialize quotas
+ * during mount time.
  */
 int vfs_quota_on_mount(int type, int format_id, struct dentry *dentry)
 {
-	struct file *f;
 	int error;
 
-	dget(dentry);	/* Get a reference for struct file */
-	f = dentry_open(dentry, NULL, O_RDWR);
-	if (IS_ERR(f)) {
-		error = PTR_ERR(f);
-		goto out_dentry;
-	}
-	error = vfs_quota_on_file(f, type, format_id);
-	if (!error)
-		return 0;
-	fput(f);
-out_dentry:
-	dput(dentry);
-	return error;
+	error = security_quota_on(dentry);
+	if (error)
+		return error;
+	return vfs_quota_on_inode(dentry->d_inode, type, format_id);
 }
 
 /* Generic routine for getting common part of quota structure */
diff --git a/fs/quota.c b/fs/quota.c
index 57e4f261e6608e..e69e8d1ada8493 100644
--- a/fs/quota.c
+++ b/fs/quota.c
@@ -14,6 +14,7 @@
 #include <linux/smp_lock.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
+#include <linux/buffer_head.h>
 
 /* Check validity of quotactl */
 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
@@ -135,16 +136,54 @@ restart:
 	return NULL;
 }
 
+void quota_sync_sb(struct super_block *sb, int type)
+{
+	int cnt;
+	struct inode *discard[MAXQUOTAS];
+
+	sb->s_qcop->quota_sync(sb, type);
+	/* This is not very clever (and fast) but currently I don't know about
+	 * any other simple way of getting quota data to disk and we must get
+	 * them there for userspace to be visible... */
+	if (sb->s_op->sync_fs)
+		sb->s_op->sync_fs(sb, 1);
+	sync_blockdev(sb->s_bdev);
+
+	/* Now when everything is written we can discard the pagecache so
+	 * that userspace sees the changes. We need i_sem and so we could
+	 * not do it inside dqonoff_sem. Moreover we need to be carefull
+	 * about races with quotaoff() (that is the reason why we have own
+	 * reference to inode). */
+	down(&sb_dqopt(sb)->dqonoff_sem);
+	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
+		discard[cnt] = NULL;
+		if (type != -1 && cnt != type)
+			continue;
+		if (!sb_has_quota_enabled(sb, cnt))
+			continue;
+		discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
+	}
+	up(&sb_dqopt(sb)->dqonoff_sem);
+	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
+		if (discard[cnt]) {
+			down(&discard[cnt]->i_sem);
+			truncate_inode_pages(&discard[cnt]->i_data, 0);
+			up(&discard[cnt]->i_sem);
+			iput(discard[cnt]);
+		}
+	}
+}
+
 void sync_dquots(struct super_block *sb, int type)
 {
 	if (sb) {
 		if (sb->s_qcop->quota_sync)
-			sb->s_qcop->quota_sync(sb, type);
+			quota_sync_sb(sb, type);
 	}
 	else {
-		while ((sb = get_super_to_sync(type)) != 0) {
+		while ((sb = get_super_to_sync(type)) != NULL) {
 			if (sb->s_qcop->quota_sync)
-				sb->s_qcop->quota_sync(sb, type);
+				quota_sync_sb(sb, type);
 			drop_super(sb);
 		}
 	}
diff --git a/fs/quota_v1.c b/fs/quota_v1.c
index a6cffdab7849c8..f3841f23306965 100644
--- a/fs/quota_v1.c
+++ b/fs/quota_v1.c
@@ -7,7 +7,6 @@
 #include <linux/init.h>
 #include <linux/module.h>
 
-#include <asm/uaccess.h>
 #include <asm/byteorder.h>
 
 MODULE_AUTHOR("Jan Kara");
@@ -41,23 +40,14 @@ static void v1_mem2disk_dqblk(struct v1_disk_dqblk *d, struct mem_dqblk *m)
 static int v1_read_dqblk(struct dquot *dquot)
 {
 	int type = dquot->dq_type;
-	struct file *filp;
-	mm_segment_t fs;
-	loff_t offset;
 	struct v1_disk_dqblk dqblk;
 
-	filp = sb_dqopt(dquot->dq_sb)->files[type];
-	if (filp == (struct file *)NULL)
+	if (!sb_dqopt(dquot->dq_sb)->files[type])
 		return -EINVAL;
 
-	/* Now we are sure filp is valid */
-	offset = v1_dqoff(dquot->dq_id);
 	/* Set structure to 0s in case read fails/is after end of file */
 	memset(&dqblk, 0, sizeof(struct v1_disk_dqblk));
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	filp->f_op->read(filp, (char *)&dqblk, sizeof(struct v1_disk_dqblk), &offset);
-	set_fs(fs);
+	dquot->dq_sb->s_op->quota_read(dquot->dq_sb, type, (char *)&dqblk, sizeof(struct v1_disk_dqblk), v1_dqoff(dquot->dq_id));
 
 	v1_disk2mem_dqblk(&dquot->dq_dqb, &dqblk);
 	if (dquot->dq_dqb.dqb_bhardlimit == 0 && dquot->dq_dqb.dqb_bsoftlimit == 0 &&
@@ -71,26 +61,18 @@ static int v1_read_dqblk(struct dquot *dquot)
 static int v1_commit_dqblk(struct dquot *dquot)
 {
 	short type = dquot->dq_type;
-	struct file *filp;
-	mm_segment_t fs;
-	loff_t offset;
 	ssize_t ret;
 	struct v1_disk_dqblk dqblk;
 
-	filp = sb_dqopt(dquot->dq_sb)->files[type];
-	offset = v1_dqoff(dquot->dq_id);
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-
 	v1_mem2disk_dqblk(&dqblk, &dquot->dq_dqb);
 	if (dquot->dq_id == 0) {
 		dqblk.dqb_btime = sb_dqopt(dquot->dq_sb)->info[type].dqi_bgrace;
 		dqblk.dqb_itime = sb_dqopt(dquot->dq_sb)->info[type].dqi_igrace;
 	}
 	ret = 0;
-	if (filp)
-		ret = filp->f_op->write(filp, (char *)&dqblk,
-					sizeof(struct v1_disk_dqblk), &offset);
+	if (sb_dqopt(dquot->dq_sb)->files[type])
+		ret = dquot->dq_sb->s_op->quota_write(dquot->dq_sb, type, (char *)&dqblk,
+					sizeof(struct v1_disk_dqblk), v1_dqoff(dquot->dq_id));
 	if (ret != sizeof(struct v1_disk_dqblk)) {
 		printk(KERN_WARNING "VFS: dquota write failed on dev %s\n",
 			dquot->dq_sb->s_id);
@@ -101,7 +83,6 @@ static int v1_commit_dqblk(struct dquot *dquot)
 	ret = 0;
 
 out:
-	set_fs(fs);
 	dqstats.writes++;
 
 	return ret;
@@ -121,14 +102,11 @@ struct v2_disk_dqheader {
 
 static int v1_check_quota_file(struct super_block *sb, int type)
 {
-	struct file *f = sb_dqopt(sb)->files[type];
-	struct inode *inode = f->f_dentry->d_inode;
+	struct inode *inode = sb_dqopt(sb)->files[type];
 	ulong blocks;
 	size_t off; 
 	struct v2_disk_dqheader dqhead;
-	mm_segment_t fs;
 	ssize_t size;
-	loff_t offset = 0;
 	loff_t isize;
 	static const uint quota_magics[] = V2_INITQMAGICS;
 
@@ -140,10 +118,7 @@ static int v1_check_quota_file(struct super_block *sb, int type)
 	if ((blocks % sizeof(struct v1_disk_dqblk) * BLOCK_SIZE + off) % sizeof(struct v1_disk_dqblk))
 		return 0;
 	/* Doublecheck whether we didn't get file with new format - with old quotactl() this could happen */
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	size = f->f_op->read(f, (char *)&dqhead, sizeof(struct v2_disk_dqheader), &offset);
-	set_fs(fs);
+	size = sb->s_op->quota_read(sb, type, (char *)&dqhead, sizeof(struct v2_disk_dqheader), 0);
 	if (size != sizeof(struct v2_disk_dqheader))
 		return 1;	/* Probably not new format */
 	if (le32_to_cpu(dqhead.dqh_magic) != quota_magics[type])
@@ -155,16 +130,10 @@ static int v1_check_quota_file(struct super_block *sb, int type)
 static int v1_read_file_info(struct super_block *sb, int type)
 {
 	struct quota_info *dqopt = sb_dqopt(sb);
-	mm_segment_t fs;
-	loff_t offset;
-	struct file *filp = dqopt->files[type];
 	struct v1_disk_dqblk dqblk;
 	int ret;
 
-	offset = v1_dqoff(0);
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	if ((ret = filp->f_op->read(filp, (char *)&dqblk, sizeof(struct v1_disk_dqblk), &offset)) != sizeof(struct v1_disk_dqblk)) {
+	if ((ret = sb->s_op->quota_read(sb, type, (char *)&dqblk, sizeof(struct v1_disk_dqblk), v1_dqoff(0))) != sizeof(struct v1_disk_dqblk)) {
 		if (ret >= 0)
 			ret = -EIO;
 		goto out;
@@ -173,38 +142,31 @@ static int v1_read_file_info(struct super_block *sb, int type)
 	dqopt->info[type].dqi_igrace = dqblk.dqb_itime ? dqblk.dqb_itime : MAX_IQ_TIME;
 	dqopt->info[type].dqi_bgrace = dqblk.dqb_btime ? dqblk.dqb_btime : MAX_DQ_TIME;
 out:
-	set_fs(fs);
 	return ret;
 }
 
 static int v1_write_file_info(struct super_block *sb, int type)
 {
 	struct quota_info *dqopt = sb_dqopt(sb);
-	mm_segment_t fs;
-	struct file *filp = dqopt->files[type];
 	struct v1_disk_dqblk dqblk;
-	loff_t offset;
 	int ret;
 
 	dqopt->info[type].dqi_flags &= ~DQF_INFO_DIRTY;
-	offset = v1_dqoff(0);
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	if ((ret = filp->f_op->read(filp, (char *)&dqblk, sizeof(struct v1_disk_dqblk), &offset)) != sizeof(struct v1_disk_dqblk)) {
+	if ((ret = sb->s_op->quota_read(sb, type, (char *)&dqblk,
+	    sizeof(struct v1_disk_dqblk), v1_dqoff(0))) != sizeof(struct v1_disk_dqblk)) {
 		if (ret >= 0)
 			ret = -EIO;
 		goto out;
 	}
 	dqblk.dqb_itime = dqopt->info[type].dqi_igrace;
 	dqblk.dqb_btime = dqopt->info[type].dqi_bgrace;
-	offset = v1_dqoff(0);
-	ret = filp->f_op->write(filp, (char *)&dqblk, sizeof(struct v1_disk_dqblk), &offset);
+	ret = sb->s_op->quota_write(sb, type, (char *)&dqblk,
+	      sizeof(struct v1_disk_dqblk), v1_dqoff(0));
 	if (ret == sizeof(struct v1_disk_dqblk))
 		ret = 0;
 	else if (ret > 0)
 		ret = -EIO;
 out:
-	set_fs(fs);
 	return ret;
 }
 
diff --git a/fs/quota_v2.c b/fs/quota_v2.c
index e12ca82cee1130..d80480712e6c67 100644
--- a/fs/quota_v2.c
+++ b/fs/quota_v2.c
@@ -13,7 +13,6 @@
 #include <linux/slab.h>
 
 #include <asm/byteorder.h>
-#include <asm/uaccess.h>
 
 MODULE_AUTHOR("Jan Kara");
 MODULE_DESCRIPTION("Quota format v2 support");
@@ -30,19 +29,15 @@ typedef char *dqbuf_t;
 static int v2_check_quota_file(struct super_block *sb, int type)
 {
 	struct v2_disk_dqheader dqhead;
-	struct file *f = sb_dqopt(sb)->files[type];
-	mm_segment_t fs;
 	ssize_t size;
-	loff_t offset = 0;
 	static const uint quota_magics[] = V2_INITQMAGICS;
 	static const uint quota_versions[] = V2_INITQVERSIONS;
  
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	size = f->f_op->read(f, (char *)&dqhead, sizeof(struct v2_disk_dqheader), &offset);
-	set_fs(fs);
-	if (size != sizeof(struct v2_disk_dqheader))
+	size = sb->s_op->quota_read(sb, type, (char *)&dqhead, sizeof(struct v2_disk_dqheader), 0);
+	if (size != sizeof(struct v2_disk_dqheader)) {
+		printk("failed read\n");
 		return 0;
+	}
 	if (le32_to_cpu(dqhead.dqh_magic) != quota_magics[type] ||
 	    le32_to_cpu(dqhead.dqh_version) != quota_versions[type])
 		return 0;
@@ -52,20 +47,15 @@ static int v2_check_quota_file(struct super_block *sb, int type)
 /* Read information header from quota file */
 static int v2_read_file_info(struct super_block *sb, int type)
 {
-	mm_segment_t fs;
 	struct v2_disk_dqinfo dinfo;
 	struct mem_dqinfo *info = sb_dqopt(sb)->info+type;
-	struct file *f = sb_dqopt(sb)->files[type];
 	ssize_t size;
-	loff_t offset = V2_DQINFOOFF;
 
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	size = f->f_op->read(f, (char *)&dinfo, sizeof(struct v2_disk_dqinfo), &offset);
-	set_fs(fs);
+	size = sb->s_op->quota_read(sb, type, (char *)&dinfo,
+	       sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
 	if (size != sizeof(struct v2_disk_dqinfo)) {
 		printk(KERN_WARNING "Can't read info structure on device %s.\n",
-			f->f_dentry->d_sb->s_id);
+			sb->s_id);
 		return -1;
 	}
 	info->dqi_bgrace = le32_to_cpu(dinfo.dqi_bgrace);
@@ -80,12 +70,9 @@ static int v2_read_file_info(struct super_block *sb, int type)
 /* Write information header to quota file */
 static int v2_write_file_info(struct super_block *sb, int type)
 {
-	mm_segment_t fs;
 	struct v2_disk_dqinfo dinfo;
 	struct mem_dqinfo *info = sb_dqopt(sb)->info+type;
-	struct file *f = sb_dqopt(sb)->files[type];
 	ssize_t size;
-	loff_t offset = V2_DQINFOOFF;
 
 	spin_lock(&dq_data_lock);
 	info->dqi_flags &= ~DQF_INFO_DIRTY;
@@ -96,13 +83,11 @@ static int v2_write_file_info(struct super_block *sb, int type)
 	dinfo.dqi_blocks = cpu_to_le32(info->u.v2_i.dqi_blocks);
 	dinfo.dqi_free_blk = cpu_to_le32(info->u.v2_i.dqi_free_blk);
 	dinfo.dqi_free_entry = cpu_to_le32(info->u.v2_i.dqi_free_entry);
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	size = f->f_op->write(f, (char *)&dinfo, sizeof(struct v2_disk_dqinfo), &offset);
-	set_fs(fs);
+	size = sb->s_op->quota_write(sb, type, (char *)&dinfo,
+	       sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
 	if (size != sizeof(struct v2_disk_dqinfo)) {
 		printk(KERN_WARNING "Can't write info structure on device %s.\n",
-			f->f_dentry->d_sb->s_id);
+			sb->s_id);
 		return -1;
 	}
 	return 0;
@@ -146,39 +131,24 @@ static inline void freedqbuf(dqbuf_t buf)
 	kfree(buf);
 }
 
-static ssize_t read_blk(struct file *filp, uint blk, dqbuf_t buf)
+static inline ssize_t read_blk(struct super_block *sb, int type, uint blk, dqbuf_t buf)
 {
-	mm_segment_t fs;
-	ssize_t ret;
-	loff_t offset = blk<<V2_DQBLKSIZE_BITS;
-
 	memset(buf, 0, V2_DQBLKSIZE);
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	ret = filp->f_op->read(filp, (char *)buf, V2_DQBLKSIZE, &offset);
-	set_fs(fs);
-	return ret;
+	return sb->s_op->quota_read(sb, type, (char *)buf,
+	       V2_DQBLKSIZE, blk << V2_DQBLKSIZE_BITS);
 }
 
-static ssize_t write_blk(struct file *filp, uint blk, dqbuf_t buf)
+static inline ssize_t write_blk(struct super_block *sb, int type, uint blk, dqbuf_t buf)
 {
-	mm_segment_t fs;
-	ssize_t ret;
-	loff_t offset = blk<<V2_DQBLKSIZE_BITS;
-
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	ret = filp->f_op->write(filp, (char *)buf, V2_DQBLKSIZE, &offset);
-	set_fs(fs);
-	return ret;
-
+	return sb->s_op->quota_write(sb, type, (char *)buf,
+	       V2_DQBLKSIZE, blk << V2_DQBLKSIZE_BITS);
 }
 
 /* Remove empty block from list and return it */
-static int get_free_dqblk(struct file *filp, int type)
+static int get_free_dqblk(struct super_block *sb, int type)
 {
 	dqbuf_t buf = getdqbuf();
-	struct mem_dqinfo *info = sb_dqinfo(filp->f_dentry->d_sb, type);
+	struct mem_dqinfo *info = sb_dqinfo(sb, type);
 	struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
 	int ret, blk;
 
@@ -186,17 +156,18 @@ static int get_free_dqblk(struct file *filp, int type)
 		return -ENOMEM;
 	if (info->u.v2_i.dqi_free_blk) {
 		blk = info->u.v2_i.dqi_free_blk;
-		if ((ret = read_blk(filp, blk, buf)) < 0)
+		if ((ret = read_blk(sb, type, blk, buf)) < 0)
 			goto out_buf;
 		info->u.v2_i.dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
 	}
 	else {
 		memset(buf, 0, V2_DQBLKSIZE);
-		if ((ret = write_blk(filp, info->u.v2_i.dqi_blocks, buf)) < 0)	/* Assure block allocation... */
+		/* Assure block allocation... */
+		if ((ret = write_blk(sb, type, info->u.v2_i.dqi_blocks, buf)) < 0)
 			goto out_buf;
 		blk = info->u.v2_i.dqi_blocks++;
 	}
-	mark_info_dirty(filp->f_dentry->d_sb, type);
+	mark_info_dirty(sb, type);
 	ret = blk;
 out_buf:
 	freedqbuf(buf);
@@ -204,9 +175,9 @@ out_buf:
 }
 
 /* Insert empty block to the list */
-static int put_free_dqblk(struct file *filp, int type, dqbuf_t buf, uint blk)
+static int put_free_dqblk(struct super_block *sb, int type, dqbuf_t buf, uint blk)
 {
-	struct mem_dqinfo *info = sb_dqinfo(filp->f_dentry->d_sb, type);
+	struct mem_dqinfo *info = sb_dqinfo(sb, type);
 	struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
 	int err;
 
@@ -214,17 +185,18 @@ static int put_free_dqblk(struct file *filp, int type, dqbuf_t buf, uint blk)
 	dh->dqdh_prev_free = cpu_to_le32(0);
 	dh->dqdh_entries = cpu_to_le16(0);
 	info->u.v2_i.dqi_free_blk = blk;
-	mark_info_dirty(filp->f_dentry->d_sb, type);
-	if ((err = write_blk(filp, blk, buf)) < 0)	/* Some strange block. We had better leave it... */
+	mark_info_dirty(sb, type);
+	/* Some strange block. We had better leave it... */
+	if ((err = write_blk(sb, type, blk, buf)) < 0)
 		return err;
 	return 0;
 }
 
 /* Remove given block from the list of blocks with free entries */
-static int remove_free_dqentry(struct file *filp, int type, dqbuf_t buf, uint blk)
+static int remove_free_dqentry(struct super_block *sb, int type, dqbuf_t buf, uint blk)
 {
 	dqbuf_t tmpbuf = getdqbuf();
-	struct mem_dqinfo *info = sb_dqinfo(filp->f_dentry->d_sb, type);
+	struct mem_dqinfo *info = sb_dqinfo(sb, type);
 	struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
 	uint nextblk = le32_to_cpu(dh->dqdh_next_free), prevblk = le32_to_cpu(dh->dqdh_prev_free);
 	int err;
@@ -232,26 +204,27 @@ static int remove_free_dqentry(struct file *filp, int type, dqbuf_t buf, uint bl
 	if (!tmpbuf)
 		return -ENOMEM;
 	if (nextblk) {
-		if ((err = read_blk(filp, nextblk, tmpbuf)) < 0)
+		if ((err = read_blk(sb, type, nextblk, tmpbuf)) < 0)
 			goto out_buf;
 		((struct v2_disk_dqdbheader *)tmpbuf)->dqdh_prev_free = dh->dqdh_prev_free;
-		if ((err = write_blk(filp, nextblk, tmpbuf)) < 0)
+		if ((err = write_blk(sb, type, nextblk, tmpbuf)) < 0)
 			goto out_buf;
 	}
 	if (prevblk) {
-		if ((err = read_blk(filp, prevblk, tmpbuf)) < 0)
+		if ((err = read_blk(sb, type, prevblk, tmpbuf)) < 0)
 			goto out_buf;
 		((struct v2_disk_dqdbheader *)tmpbuf)->dqdh_next_free = dh->dqdh_next_free;
-		if ((err = write_blk(filp, prevblk, tmpbuf)) < 0)
+		if ((err = write_blk(sb, type, prevblk, tmpbuf)) < 0)
 			goto out_buf;
 	}
 	else {
 		info->u.v2_i.dqi_free_entry = nextblk;
-		mark_info_dirty(filp->f_dentry->d_sb, type);
+		mark_info_dirty(sb, type);
 	}
 	freedqbuf(tmpbuf);
 	dh->dqdh_next_free = dh->dqdh_prev_free = cpu_to_le32(0);
-	if (write_blk(filp, blk, buf) < 0)	/* No matter whether write succeeds block is out of list */
+	/* No matter whether write succeeds block is out of list */
+	if (write_blk(sb, type, blk, buf) < 0)
 		printk(KERN_ERR "VFS: Can't write block (%u) with free entries.\n", blk);
 	return 0;
 out_buf:
@@ -260,10 +233,10 @@ out_buf:
 }
 
 /* Insert given block to the beginning of list with free entries */
-static int insert_free_dqentry(struct file *filp, int type, dqbuf_t buf, uint blk)
+static int insert_free_dqentry(struct super_block *sb, int type, dqbuf_t buf, uint blk)
 {
 	dqbuf_t tmpbuf = getdqbuf();
-	struct mem_dqinfo *info = sb_dqinfo(filp->f_dentry->d_sb, type);
+	struct mem_dqinfo *info = sb_dqinfo(sb, type);
 	struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
 	int err;
 
@@ -271,18 +244,18 @@ static int insert_free_dqentry(struct file *filp, int type, dqbuf_t buf, uint bl
 		return -ENOMEM;
 	dh->dqdh_next_free = cpu_to_le32(info->u.v2_i.dqi_free_entry);
 	dh->dqdh_prev_free = cpu_to_le32(0);
-	if ((err = write_blk(filp, blk, buf)) < 0)
+	if ((err = write_blk(sb, type, blk, buf)) < 0)
 		goto out_buf;
 	if (info->u.v2_i.dqi_free_entry) {
-		if ((err = read_blk(filp, info->u.v2_i.dqi_free_entry, tmpbuf)) < 0)
+		if ((err = read_blk(sb, type, info->u.v2_i.dqi_free_entry, tmpbuf)) < 0)
 			goto out_buf;
 		((struct v2_disk_dqdbheader *)tmpbuf)->dqdh_prev_free = cpu_to_le32(blk);
-		if ((err = write_blk(filp, info->u.v2_i.dqi_free_entry, tmpbuf)) < 0)
+		if ((err = write_blk(sb, type, info->u.v2_i.dqi_free_entry, tmpbuf)) < 0)
 			goto out_buf;
 	}
 	freedqbuf(tmpbuf);
 	info->u.v2_i.dqi_free_entry = blk;
-	mark_info_dirty(filp->f_dentry->d_sb, type);
+	mark_info_dirty(sb, type);
 	return 0;
 out_buf:
 	freedqbuf(tmpbuf);
@@ -292,8 +265,8 @@ out_buf:
 /* Find space for dquot */
 static uint find_free_dqentry(struct dquot *dquot, int *err)
 {
-	struct file *filp = sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
-	struct mem_dqinfo *info = sb_dqopt(dquot->dq_sb)->info+dquot->dq_type;
+	struct super_block *sb = dquot->dq_sb;
+	struct mem_dqinfo *info = sb_dqopt(sb)->info+dquot->dq_type;
 	uint blk, i;
 	struct v2_disk_dqdbheader *dh;
 	struct v2_disk_dqblk *ddquot;
@@ -309,22 +282,23 @@ static uint find_free_dqentry(struct dquot *dquot, int *err)
 	ddquot = GETENTRIES(buf);
 	if (info->u.v2_i.dqi_free_entry) {
 		blk = info->u.v2_i.dqi_free_entry;
-		if ((*err = read_blk(filp, blk, buf)) < 0)
+		if ((*err = read_blk(sb, dquot->dq_type, blk, buf)) < 0)
 			goto out_buf;
 	}
 	else {
-		blk = get_free_dqblk(filp, dquot->dq_type);
+		blk = get_free_dqblk(sb, dquot->dq_type);
 		if ((int)blk < 0) {
 			*err = blk;
 			freedqbuf(buf);
 			return 0;
 		}
 		memset(buf, 0, V2_DQBLKSIZE);
-		info->u.v2_i.dqi_free_entry = blk;	/* This is enough as block is already zeroed and entry list is empty... */
-		mark_info_dirty(dquot->dq_sb, dquot->dq_type);
+		/* This is enough as block is already zeroed and entry list is empty... */
+		info->u.v2_i.dqi_free_entry = blk;
+		mark_info_dirty(sb, dquot->dq_type);
 	}
 	if (le16_to_cpu(dh->dqdh_entries)+1 >= V2_DQSTRINBLK)	/* Block will be full? */
-		if ((*err = remove_free_dqentry(filp, dquot->dq_type, buf, blk)) < 0) {
+		if ((*err = remove_free_dqentry(sb, dquot->dq_type, buf, blk)) < 0) {
 			printk(KERN_ERR "VFS: find_free_dqentry(): Can't remove block (%u) from entry free list.\n", blk);
 			goto out_buf;
 		}
@@ -339,7 +313,7 @@ static uint find_free_dqentry(struct dquot *dquot, int *err)
 		goto out_buf;
 	}
 #endif
-	if ((*err = write_blk(filp, blk, buf)) < 0) {
+	if ((*err = write_blk(sb, dquot->dq_type, blk, buf)) < 0) {
 		printk(KERN_ERR "VFS: find_free_dqentry(): Can't write quota data block %u.\n", blk);
 		goto out_buf;
 	}
@@ -354,7 +328,7 @@ out_buf:
 /* Insert reference to structure into the trie */
 static int do_insert_tree(struct dquot *dquot, uint *treeblk, int depth)
 {
-	struct file *filp = sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
+	struct super_block *sb = dquot->dq_sb;
 	dqbuf_t buf;
 	int ret = 0, newson = 0, newact = 0;
 	__le32 *ref;
@@ -363,7 +337,7 @@ static int do_insert_tree(struct dquot *dquot, uint *treeblk, int depth)
 	if (!(buf = getdqbuf()))
 		return -ENOMEM;
 	if (!*treeblk) {
-		ret = get_free_dqblk(filp, dquot->dq_type);
+		ret = get_free_dqblk(sb, dquot->dq_type);
 		if (ret < 0)
 			goto out_buf;
 		*treeblk = ret;
@@ -371,7 +345,7 @@ static int do_insert_tree(struct dquot *dquot, uint *treeblk, int depth)
 		newact = 1;
 	}
 	else {
-		if ((ret = read_blk(filp, *treeblk, buf)) < 0) {
+		if ((ret = read_blk(sb, dquot->dq_type, *treeblk, buf)) < 0) {
 			printk(KERN_ERR "VFS: Can't read tree quota block %u.\n", *treeblk);
 			goto out_buf;
 		}
@@ -394,10 +368,10 @@ static int do_insert_tree(struct dquot *dquot, uint *treeblk, int depth)
 		ret = do_insert_tree(dquot, &newblk, depth+1);
 	if (newson && ret >= 0) {
 		ref[GETIDINDEX(dquot->dq_id, depth)] = cpu_to_le32(newblk);
-		ret = write_blk(filp, *treeblk, buf);
+		ret = write_blk(sb, dquot->dq_type, *treeblk, buf);
 	}
 	else if (newact && ret < 0)
-		put_free_dqblk(filp, dquot->dq_type, buf, *treeblk);
+		put_free_dqblk(sb, dquot->dq_type, buf, *treeblk);
 out_buf:
 	freedqbuf(buf);
 	return ret;
@@ -416,20 +390,15 @@ static inline int dq_insert_tree(struct dquot *dquot)
 static int v2_write_dquot(struct dquot *dquot)
 {
 	int type = dquot->dq_type;
-	struct file *filp;
-	mm_segment_t fs;
-	loff_t offset;
 	ssize_t ret;
 	struct v2_disk_dqblk ddquot, empty;
 
 	/* dq_off is guarded by dqio_sem */
 	if (!dquot->dq_off)
 		if ((ret = dq_insert_tree(dquot)) < 0) {
-			printk(KERN_ERR "VFS: Error %Zd occurred while creating quota.\n", ret);
+			printk(KERN_ERR "VFS: Error %d occurred while creating quota.\n", ret);
 			return ret;
 		}
-	filp = sb_dqopt(dquot->dq_sb)->files[type];
-	offset = dquot->dq_off;
 	spin_lock(&dq_data_lock);
 	mem2diskdqb(&ddquot, &dquot->dq_dqb, dquot->dq_id);
 	/* Argh... We may need to write structure full of zeroes but that would be
@@ -439,10 +408,8 @@ static int v2_write_dquot(struct dquot *dquot)
 	if (!memcmp(&empty, &ddquot, sizeof(struct v2_disk_dqblk)))
 		ddquot.dqb_itime = cpu_to_le64(1);
 	spin_unlock(&dq_data_lock);
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	ret = filp->f_op->write(filp, (char *)&ddquot, sizeof(struct v2_disk_dqblk), &offset);
-	set_fs(fs);
+	ret = dquot->dq_sb->s_op->quota_write(dquot->dq_sb, type,
+	      (char *)&ddquot, sizeof(struct v2_disk_dqblk), dquot->dq_off);
 	if (ret != sizeof(struct v2_disk_dqblk)) {
 		printk(KERN_WARNING "VFS: dquota write failed on dev %s\n", dquot->dq_sb->s_id);
 		if (ret >= 0)
@@ -458,7 +425,8 @@ static int v2_write_dquot(struct dquot *dquot)
 /* Free dquot entry in data block */
 static int free_dqentry(struct dquot *dquot, uint blk)
 {
-	struct file *filp = sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
+	struct super_block *sb = dquot->dq_sb;
+	int type = dquot->dq_type;
 	struct v2_disk_dqdbheader *dh;
 	dqbuf_t buf = getdqbuf();
 	int ret = 0;
@@ -466,34 +434,39 @@ static int free_dqentry(struct dquot *dquot, uint blk)
 	if (!buf)
 		return -ENOMEM;
 	if (dquot->dq_off >> V2_DQBLKSIZE_BITS != blk) {
-		printk(KERN_ERR "VFS: Quota structure has offset to other block (%u) than it should (%u).\n", blk, (uint)(dquot->dq_off >> V2_DQBLKSIZE_BITS));
+		printk(KERN_ERR "VFS: Quota structure has offset to other "
+		  "block (%u) than it should (%u).\n", blk,
+		  (uint)(dquot->dq_off >> V2_DQBLKSIZE_BITS));
 		goto out_buf;
 	}
-	if ((ret = read_blk(filp, blk, buf)) < 0) {
+	if ((ret = read_blk(sb, type, blk, buf)) < 0) {
 		printk(KERN_ERR "VFS: Can't read quota data block %u\n", blk);
 		goto out_buf;
 	}
 	dh = (struct v2_disk_dqdbheader *)buf;
 	dh->dqdh_entries = cpu_to_le16(le16_to_cpu(dh->dqdh_entries)-1);
 	if (!le16_to_cpu(dh->dqdh_entries)) {	/* Block got free? */
-		if ((ret = remove_free_dqentry(filp, dquot->dq_type, buf, blk)) < 0 ||
-		    (ret = put_free_dqblk(filp, dquot->dq_type, buf, blk)) < 0) {
-			printk(KERN_ERR "VFS: Can't move quota data block (%u) to free list.\n", blk);
+		if ((ret = remove_free_dqentry(sb, type, buf, blk)) < 0 ||
+		    (ret = put_free_dqblk(sb, type, buf, blk)) < 0) {
+			printk(KERN_ERR "VFS: Can't move quota data block (%u) "
+			  "to free list.\n", blk);
 			goto out_buf;
 		}
 	}
 	else {
-		memset(buf+(dquot->dq_off & ((1 << V2_DQBLKSIZE_BITS)-1)), 0, sizeof(struct v2_disk_dqblk));
+		memset(buf+(dquot->dq_off & ((1 << V2_DQBLKSIZE_BITS)-1)), 0,
+		  sizeof(struct v2_disk_dqblk));
 		if (le16_to_cpu(dh->dqdh_entries) == V2_DQSTRINBLK-1) {
 			/* Insert will write block itself */
-			if ((ret = insert_free_dqentry(filp, dquot->dq_type, buf, blk)) < 0) {
+			if ((ret = insert_free_dqentry(sb, type, buf, blk)) < 0) {
 				printk(KERN_ERR "VFS: Can't insert quota data block (%u) to free entry list.\n", blk);
 				goto out_buf;
 			}
 		}
 		else
-			if ((ret = write_blk(filp, blk, buf)) < 0) {
-				printk(KERN_ERR "VFS: Can't write quota data block %u\n", blk);
+			if ((ret = write_blk(sb, type, blk, buf)) < 0) {
+				printk(KERN_ERR "VFS: Can't write quota data "
+				  "block %u\n", blk);
 				goto out_buf;
 			}
 	}
@@ -506,7 +479,8 @@ out_buf:
 /* Remove reference to dquot from tree */
 static int remove_tree(struct dquot *dquot, uint *blk, int depth)
 {
-	struct file *filp = sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
+	struct super_block *sb = dquot->dq_sb;
+	int type = dquot->dq_type;
 	dqbuf_t buf = getdqbuf();
 	int ret = 0;
 	uint newblk;
@@ -514,7 +488,7 @@ static int remove_tree(struct dquot *dquot, uint *blk, int depth)
 	
 	if (!buf)
 		return -ENOMEM;
-	if ((ret = read_blk(filp, *blk, buf)) < 0) {
+	if ((ret = read_blk(sb, type, *blk, buf)) < 0) {
 		printk(KERN_ERR "VFS: Can't read quota data block %u\n", *blk);
 		goto out_buf;
 	}
@@ -530,12 +504,13 @@ static int remove_tree(struct dquot *dquot, uint *blk, int depth)
 		ref[GETIDINDEX(dquot->dq_id, depth)] = cpu_to_le32(0);
 		for (i = 0; i < V2_DQBLKSIZE && !buf[i]; i++);	/* Block got empty? */
 		if (i == V2_DQBLKSIZE) {
-			put_free_dqblk(filp, dquot->dq_type, buf, *blk);
+			put_free_dqblk(sb, type, buf, *blk);
 			*blk = 0;
 		}
 		else
-			if ((ret = write_blk(filp, *blk, buf)) < 0)
-				printk(KERN_ERR "VFS: Can't write quota tree block %u.\n", *blk);
+			if ((ret = write_blk(sb, type, *blk, buf)) < 0)
+				printk(KERN_ERR "VFS: Can't write quota tree "
+				  "block %u.\n", *blk);
 	}
 out_buf:
 	freedqbuf(buf);
@@ -555,7 +530,6 @@ static int v2_delete_dquot(struct dquot *dquot)
 /* Find entry in block */
 static loff_t find_block_dqentry(struct dquot *dquot, uint blk)
 {
-	struct file *filp = sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
 	dqbuf_t buf = getdqbuf();
 	loff_t ret = 0;
 	int i;
@@ -563,27 +537,31 @@ static loff_t find_block_dqentry(struct dquot *dquot, uint blk)
 
 	if (!buf)
 		return -ENOMEM;
-	if ((ret = read_blk(filp, blk, buf)) < 0) {
+	if ((ret = read_blk(dquot->dq_sb, dquot->dq_type, blk, buf)) < 0) {
 		printk(KERN_ERR "VFS: Can't read quota tree block %u.\n", blk);
 		goto out_buf;
 	}
 	if (dquot->dq_id)
-		for (i = 0; i < V2_DQSTRINBLK && le32_to_cpu(ddquot[i].dqb_id) != dquot->dq_id; i++);
+		for (i = 0; i < V2_DQSTRINBLK &&
+		     le32_to_cpu(ddquot[i].dqb_id) != dquot->dq_id; i++);
 	else {	/* ID 0 as a bit more complicated searching... */
 		struct v2_disk_dqblk fakedquot;
 
 		memset(&fakedquot, 0, sizeof(struct v2_disk_dqblk));
 		for (i = 0; i < V2_DQSTRINBLK; i++)
-			if (!le32_to_cpu(ddquot[i].dqb_id) && memcmp(&fakedquot, ddquot+i, sizeof(struct v2_disk_dqblk)))
+			if (!le32_to_cpu(ddquot[i].dqb_id) &&
+			    memcmp(&fakedquot, ddquot+i, sizeof(struct v2_disk_dqblk)))
 				break;
 	}
 	if (i == V2_DQSTRINBLK) {
-		printk(KERN_ERR "VFS: Quota for id %u referenced but not present.\n", dquot->dq_id);
+		printk(KERN_ERR "VFS: Quota for id %u referenced "
+		  "but not present.\n", dquot->dq_id);
 		ret = -EIO;
 		goto out_buf;
 	}
 	else
-		ret = (blk << V2_DQBLKSIZE_BITS) + sizeof(struct v2_disk_dqdbheader) + i * sizeof(struct v2_disk_dqblk);
+		ret = (blk << V2_DQBLKSIZE_BITS) + sizeof(struct
+		  v2_disk_dqdbheader) + i * sizeof(struct v2_disk_dqblk);
 out_buf:
 	freedqbuf(buf);
 	return ret;
@@ -592,14 +570,13 @@ out_buf:
 /* Find entry for given id in the tree */
 static loff_t find_tree_dqentry(struct dquot *dquot, uint blk, int depth)
 {
-	struct file *filp = sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
 	dqbuf_t buf = getdqbuf();
 	loff_t ret = 0;
 	__le32 *ref = (__le32 *)buf;
 
 	if (!buf)
 		return -ENOMEM;
-	if ((ret = read_blk(filp, blk, buf)) < 0) {
+	if ((ret = read_blk(dquot->dq_sb, dquot->dq_type, blk, buf)) < 0) {
 		printk(KERN_ERR "VFS: Can't read quota tree block %u.\n", blk);
 		goto out_buf;
 	}
@@ -625,16 +602,13 @@ static inline loff_t find_dqentry(struct dquot *dquot)
 static int v2_read_dquot(struct dquot *dquot)
 {
 	int type = dquot->dq_type;
-	struct file *filp;
-	mm_segment_t fs;
 	loff_t offset;
 	struct v2_disk_dqblk ddquot, empty;
 	int ret = 0;
 
-	filp = sb_dqopt(dquot->dq_sb)->files[type];
-
 #ifdef __QUOTA_V2_PARANOIA
-	if (!filp || !dquot->dq_sb) {	/* Invalidated quota? */
+	/* Invalidated quota? */
+	if (!dquot->dq_sb || !sb_dqopt(dquot->dq_sb)->files[type]) {
 		printk(KERN_ERR "VFS: Quota invalidated while reading!\n");
 		return -EIO;
 	}
@@ -642,7 +616,8 @@ static int v2_read_dquot(struct dquot *dquot)
 	offset = find_dqentry(dquot);
 	if (offset <= 0) {	/* Entry not present? */
 		if (offset < 0)
-			printk(KERN_ERR "VFS: Can't read quota structure for id %u.\n", dquot->dq_id);
+			printk(KERN_ERR "VFS: Can't read quota "
+			  "structure for id %u.\n", dquot->dq_id);
 		dquot->dq_off = 0;
 		set_bit(DQ_FAKE_B, &dquot->dq_flags);
 		memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
@@ -650,12 +625,13 @@ static int v2_read_dquot(struct dquot *dquot)
 	}
 	else {
 		dquot->dq_off = offset;
-		fs = get_fs();
-		set_fs(KERNEL_DS);
-		if ((ret = filp->f_op->read(filp, (char *)&ddquot, sizeof(struct v2_disk_dqblk), &offset)) != sizeof(struct v2_disk_dqblk)) {
+		if ((ret = dquot->dq_sb->s_op->quota_read(dquot->dq_sb, type,
+		    (char *)&ddquot, sizeof(struct v2_disk_dqblk), offset))
+		    != sizeof(struct v2_disk_dqblk)) {
 			if (ret >= 0)
 				ret = -EIO;
-			printk(KERN_ERR "VFS: Error while reading quota structure for id %u.\n", dquot->dq_id);
+			printk(KERN_ERR "VFS: Error while reading quota "
+			  "structure for id %u.\n", dquot->dq_id);
 			memset(&ddquot, 0, sizeof(struct v2_disk_dqblk));
 		}
 		else {
@@ -666,7 +642,6 @@ static int v2_read_dquot(struct dquot *dquot)
 			if (!memcmp(&empty, &ddquot, sizeof(struct v2_disk_dqblk)))
 				ddquot.dqb_itime = 0;
 		}
-		set_fs(fs);
 		disk2memdqb(&dquot->dq_dqb, &ddquot);
 		if (!dquot->dq_dqb.dqb_bhardlimit &&
 			!dquot->dq_dqb.dqb_bsoftlimit &&