Ext4 regression fixes for 3.4

This fixes a scalability problem reported by Andi Kleen and Tim Chen;
 they were quite secretive about the precise nature of their workload,
 but they later admitted that it only showed up when they were using a
 large sparse file, so the amount of data I/O that was needed was close
 to zero.  I'm not sure how realistic this is and it's only a
 regression if you consider changes made since 2.6.39 to be a
 "regression" vis-a-vis the policy regarding post-merge window bug
 fixes, but Linus agreed it was worth fixing, so I'm including it in
 this pull request.
 
 This also fixes the journalled quota mount options, which I
 accidentally broke while I was cleaning up the mount option handling.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 regression fixes from Ted Ts'o:
 "This fixes a scalability problem reported by Andi Kleen and Tim Chen;
  they were quite secretive about the precise nature of their workload,
  but they later admitted that it only showed up when they were using a
  large sparse file, so the amount of data I/O that was needed was close
  to zero.

  I'm not sure how realistic this is and it's only a regression if you
  consider changes made since 2.6.39 to be a "regression" vis-a-vis the
  policy regarding post-merge window bug fixes, but Linus agreed it was
  worth fixing, so I'm including it in this pull request.

  This also fixes the journalled quota mount options, which I
  accidentally broke while I was cleaning up the mount option handling."

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix handling of journalled quota options
  ext4: address scalability issue by removing extent cache statistics

fs/ext4/ext4.h

@@ -1203,9 +1203,6 @@ struct ext4_sb_info {
 	unsigned long s_ext_blocks;
 	unsigned long s_ext_extents;
 #endif
-	/* ext4 extent cache stats */
-	unsigned long extent_cache_hits;
-	unsigned long extent_cache_misses;
 
 	/* for buddy allocator */
 	struct ext4_group_info ***s_group_info;

fs/ext4/extents.c

@@ -2066,10 +2066,6 @@ static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
 		ret = 1;
 	}
 errout:
-	if (!ret)
-		sbi->extent_cache_misses++;
-	else
-		sbi->extent_cache_hits++;
 	trace_ext4_ext_in_cache(inode, block, ret);
 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 	return ret;

fs/ext4/super.c

@@ -1305,20 +1305,20 @@ static int set_qf_name(struct super_block *sb, int qtype, substring_t *args)
 		ext4_msg(sb, KERN_ERR,
 			"Cannot change journaled "
 			"quota options when quota turned on");
-		return 0;
+		return -1;
 	}
 	qname = match_strdup(args);
 	if (!qname) {
 		ext4_msg(sb, KERN_ERR,
 			"Not enough memory for storing quotafile name");
-		return 0;
+		return -1;
 	}
 	if (sbi->s_qf_names[qtype] &&
 		strcmp(sbi->s_qf_names[qtype], qname)) {
 		ext4_msg(sb, KERN_ERR,
 			"%s quota file already specified", QTYPE2NAME(qtype));
 		kfree(qname);
-		return 0;
+		return -1;
 	}
 	sbi->s_qf_names[qtype] = qname;
 	if (strchr(sbi->s_qf_names[qtype], '/')) {
@@ -1326,7 +1326,7 @@ static int set_qf_name(struct super_block *sb, int qtype, substring_t *args)
 			"quotafile must be on filesystem root");
 		kfree(sbi->s_qf_names[qtype]);
 		sbi->s_qf_names[qtype] = NULL;
-		return 0;
+		return -1;
 	}
 	set_opt(sb, QUOTA);
 	return 1;
@@ -1341,7 +1341,7 @@ static int clear_qf_name(struct super_block *sb, int qtype)
 		sbi->s_qf_names[qtype]) {
 		ext4_msg(sb, KERN_ERR, "Cannot change journaled quota options"
 			" when quota turned on");
-		return 0;
+		return -1;
 	}
 	/*
 	 * The space will be released later when all options are confirmed
@@ -1450,6 +1450,16 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 	const struct mount_opts *m;
 	int arg = 0;
 
+#ifdef CONFIG_QUOTA
+	if (token == Opt_usrjquota)
+		return set_qf_name(sb, USRQUOTA, &args[0]);
+	else if (token == Opt_grpjquota)
+		return set_qf_name(sb, GRPQUOTA, &args[0]);
+	else if (token == Opt_offusrjquota)
+		return clear_qf_name(sb, USRQUOTA);
+	else if (token == Opt_offgrpjquota)
+		return clear_qf_name(sb, GRPQUOTA);
+#endif
 	if (args->from && match_int(args, &arg))
 		return -1;
 	switch (token) {
@@ -1549,18 +1559,6 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 				sbi->s_mount_opt |= m->mount_opt;
 			}
 #ifdef CONFIG_QUOTA
-		} else if (token == Opt_usrjquota) {
-			if (!set_qf_name(sb, USRQUOTA, &args[0]))
-				return -1;
-		} else if (token == Opt_grpjquota) {
-			if (!set_qf_name(sb, GRPQUOTA, &args[0]))
-				return -1;
-		} else if (token == Opt_offusrjquota) {
-			if (!clear_qf_name(sb, USRQUOTA))
-				return -1;
-		} else if (token == Opt_offgrpjquota) {
-			if (!clear_qf_name(sb, GRPQUOTA))
-				return -1;
 		} else if (m->flags & MOPT_QFMT) {
 			if (sb_any_quota_loaded(sb) &&
 			    sbi->s_jquota_fmt != m->mount_opt) {
@@ -2366,18 +2364,6 @@ static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a,
 			  EXT4_SB(sb)->s_sectors_written_start) >> 1)));
 }
 
-static ssize_t extent_cache_hits_show(struct ext4_attr *a,
-				      struct ext4_sb_info *sbi, char *buf)
-{
-	return snprintf(buf, PAGE_SIZE, "%lu\n", sbi->extent_cache_hits);
-}
-
-static ssize_t extent_cache_misses_show(struct ext4_attr *a,
-					struct ext4_sb_info *sbi, char *buf)
-{
-	return snprintf(buf, PAGE_SIZE, "%lu\n", sbi->extent_cache_misses);
-}
-
 static ssize_t inode_readahead_blks_store(struct ext4_attr *a,
 					  struct ext4_sb_info *sbi,
 					  const char *buf, size_t count)
@@ -2435,8 +2421,6 @@ static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)
 EXT4_RO_ATTR(delayed_allocation_blocks);
 EXT4_RO_ATTR(session_write_kbytes);
 EXT4_RO_ATTR(lifetime_write_kbytes);
-EXT4_RO_ATTR(extent_cache_hits);
-EXT4_RO_ATTR(extent_cache_misses);
 EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show,
 		 inode_readahead_blks_store, s_inode_readahead_blks);
 EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
@@ -2452,8 +2436,6 @@ static struct attribute *ext4_attrs[] = {
 	ATTR_LIST(delayed_allocation_blocks),
 	ATTR_LIST(session_write_kbytes),
 	ATTR_LIST(lifetime_write_kbytes),
-	ATTR_LIST(extent_cache_hits),
-	ATTR_LIST(extent_cache_misses),
 	ATTR_LIST(inode_readahead_blks),
 	ATTR_LIST(inode_goal),
 	ATTR_LIST(mb_stats),