Index: linux-stage/fs/ext4/ext4.h
===================================================================
--- linux-stage.orig/fs/ext4/ext4.h
+++ linux-stage/fs/ext4/ext4.h
@@ -1242,6 +1242,8 @@ struct ext4_super_block {
 #define EXT4_MF_MNTDIR_SAMPLED	0x0001
 #define EXT4_MF_FS_ABORTED	0x0002	/* Fatal error detected */
 
+#define EXT4_MAX_PREALLOC_TABLE	64
+
 /*
  * fourth extended-fs super-block data in memory
  */
@@ -1331,11 +1333,13 @@ struct ext4_sb_info {
 
 	/* tunables */
 	unsigned long s_stripe;
-	unsigned int s_mb_stream_request;
+	unsigned long s_mb_small_req;
+	unsigned long s_mb_large_req;
 	unsigned int s_mb_max_to_scan;
 	unsigned int s_mb_min_to_scan;
 	unsigned int s_mb_stats;
 	unsigned int s_mb_order2_reqs;
+	unsigned long *s_mb_prealloc_table;
 	unsigned int s_mb_group_prealloc;
 	unsigned int s_max_dir_size_kb;
 	/* where last allocation was done - for stream allocation */
Index: linux-stage/fs/ext4/mballoc.c
===================================================================
--- linux-stage.orig/fs/ext4/mballoc.c
+++ linux-stage/fs/ext4/mballoc.c
@@ -2303,6 +2303,102 @@ static const struct seq_operations ext4_
 	.show   = ext4_mb_seq_groups_show,
 };
 
+#define EXT4_MB_PREALLOC_TABLE          "prealloc_table"
+
+static int ext4_mb_check_and_update_prealloc(struct ext4_sb_info *sbi,
+						 char *str, size_t cnt,
+						 int update)
+{
+	unsigned long value;
+	unsigned long prev = 0;
+	char *cur;
+	char *next;
+	char *end;
+	int num = 0;
+
+	cur = str;
+	end = str + cnt;
+	while (cur < end) {
+		while ((cur < end) && (*cur == ' ')) cur++;
+		value = simple_strtol(cur, &next, 0);
+		if (value == 0)
+			break;
+		if (cur == next)
+			return -EINVAL;
+
+		cur = next;
+
+		if (value > (sbi->s_blocks_per_group - 1 - 1 - sbi->s_itb_per_group))
+			return -EINVAL;
+
+		/* they should add values in order */
+		if (value <= prev)
+			return -EINVAL;
+
+		if (update)
+			sbi->s_mb_prealloc_table[num] = value;
+
+		prev = value;
+		num++;
+	}
+
+	if (num > EXT4_MAX_PREALLOC_TABLE - 1)
+		return -EOVERFLOW;
+
+	if (update)
+		sbi->s_mb_prealloc_table[num] = 0;
+
+	return 0;
+}
+
+static ssize_t ext4_mb_prealloc_table_proc_write(struct file *file,
+					     const char __user *buf,
+					     size_t cnt, loff_t *pos)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(PDE_DATA(file_inode(file)));
+	char str[128];
+	int rc;
+
+	if (cnt >= sizeof(str))
+		return -EINVAL;
+	if (copy_from_user(str, buf, cnt))
+		return -EFAULT;
+
+	rc = ext4_mb_check_and_update_prealloc(sbi, str, cnt, 0);
+	if (rc)
+		return rc;
+
+	rc = ext4_mb_check_and_update_prealloc(sbi, str, cnt, 1);
+	return rc ? rc : cnt;
+}
+
+static int mb_prealloc_table_seq_show(struct seq_file *m, void *v)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(m->private);
+	int i;
+
+	for (i = 0; i < EXT4_MAX_PREALLOC_TABLE &&
+			sbi->s_mb_prealloc_table[i] != 0; i++)
+		seq_printf(m, "%ld ", sbi->s_mb_prealloc_table[i]);
+	seq_printf(m, "\n");
+
+	return 0;
+}
+
+static int mb_prealloc_table_seq_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mb_prealloc_table_seq_show, PDE_DATA(inode));
+}
+
+static const struct file_operations ext4_mb_prealloc_seq_fops = {
+	.owner   = THIS_MODULE,
+	.open    = mb_prealloc_table_seq_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = single_release,
+	.write   = ext4_mb_prealloc_table_proc_write,
+};
+
 static int ext4_mb_seq_groups_open(struct inode *inode, struct file *file)
 {
 	struct super_block *sb = PDE_DATA(inode);
@@ -2552,7 +2648,7 @@ static int ext4_groupinfo_create_slab(si
 int ext4_mb_init(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	unsigned i, j;
+	unsigned i, j, k, l;
 	unsigned offset, offset_incr;
 	unsigned max;
 	int ret;
@@ -2599,7 +2695,6 @@ int ext4_mb_init(struct super_block *sb)
 	sbi->s_mb_max_to_scan = MB_DEFAULT_MAX_TO_SCAN;
 	sbi->s_mb_min_to_scan = MB_DEFAULT_MIN_TO_SCAN;
 	sbi->s_mb_stats = MB_DEFAULT_STATS;
-	sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD;
 	sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
 	/*
 	 * The default group preallocation is 512, which for 4k block
@@ -2623,9 +2718,29 @@ int ext4_mb_init(struct super_block *sb)
 	 * RAID stripe size so that preallocations don't fragment
 	 * the stripes.
 	 */
-	if (sbi->s_stripe > 1) {
-		sbi->s_mb_group_prealloc = roundup(
-			sbi->s_mb_group_prealloc, sbi->s_stripe);
+
+	/* Allocate table once */
+	sbi->s_mb_prealloc_table = kzalloc(
+		EXT4_MAX_PREALLOC_TABLE * sizeof(unsigned long), GFP_NOFS);
+	if (sbi->s_mb_prealloc_table == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (sbi->s_stripe == 0) {
+		for (k = 0, l = 4; k <= 9; ++k, l *= 2)
+			sbi->s_mb_prealloc_table[k] = l;
+
+		sbi->s_mb_small_req = 256;
+		sbi->s_mb_large_req = 1024;
+		sbi->s_mb_group_prealloc = 512;
+	} else {
+		for (k = 0, l = sbi->s_stripe; k <= 2; ++k, l *= 2)
+			sbi->s_mb_prealloc_table[k] = l;
+
+		sbi->s_mb_small_req = sbi->s_stripe;
+		sbi->s_mb_large_req = sbi->s_stripe * 8;
+		sbi->s_mb_group_prealloc = sbi->s_stripe * 4;
 	}
 
 	sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
@@ -2647,9 +2762,13 @@ int ext4_mb_init(struct super_block *sb)
 	if (ret != 0)
 		goto out_free_locality_groups;
 
-	if (sbi->s_proc)
+	if (sbi->s_proc) {
 		proc_create_data("mb_groups", S_IRUGO, sbi->s_proc,
 				 &ext4_mb_seq_groups_fops, sb);
+		proc_create_data(EXT4_MB_PREALLOC_TABLE, S_IFREG | S_IRUGO |
+				 S_IWUSR, sbi->s_proc,
+				 &ext4_mb_prealloc_seq_fops, sb);
+	}
 
 	return 0;
 
@@ -2657,6 +2776,7 @@ out_free_locality_groups:
 	free_percpu(sbi->s_locality_groups);
 	sbi->s_locality_groups = NULL;
 out:
+	kfree(sbi->s_mb_prealloc_table);
 	kfree(sbi->s_mb_offsets);
 	sbi->s_mb_offsets = NULL;
 	kfree(sbi->s_mb_maxs);
@@ -2691,8 +2811,10 @@ int ext4_mb_release(struct super_block *
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct kmem_cache *cachep = get_groupinfo_cache(sb->s_blocksize_bits);
 
-	if (sbi->s_proc)
+	if (sbi->s_proc) {
 		remove_proc_entry("mb_groups", sbi->s_proc);
+		remove_proc_entry(EXT4_MB_PREALLOC_TABLE, sbi->s_proc);
+	}
 
 	if (sbi->s_group_info) {
 		for (i = 0; i < ngroups; i++) {
@@ -2877,7 +2999,6 @@ ext4_mb_mark_diskspace_used(struct ext4_
 	int err, len;
 
 	BUG_ON(ac->ac_status != AC_STATUS_FOUND);
-	BUG_ON(ac->ac_b_ex.fe_len <= 0);
 
 	sb = ac->ac_sb;
 	sbi = EXT4_SB(sb);
@@ -3004,13 +3125,14 @@ ext4_mb_normalize_request(struct ext4_al
 				struct ext4_allocation_request *ar)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
-	int bsbits, max;
+	int bsbits, i, wind;
 	ext4_lblk_t end;
-	loff_t size, start_off;
+	loff_t size;
 	loff_t orig_size __maybe_unused;
 	ext4_lblk_t start;
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_prealloc_space *pa;
+	unsigned long value, last_non_zero;
 
 	/* do normalize only data requests, metadata requests
 	   do not need preallocation */
@@ -3039,51 +3161,46 @@ ext4_mb_normalize_request(struct ext4_al
 	size = size << bsbits;
 	if (size < i_size_read(ac->ac_inode))
 		size = i_size_read(ac->ac_inode);
-	orig_size = size;
+	size = (size + ac->ac_sb->s_blocksize - 1) >> bsbits;
 
-	/* max size of free chunks */
-	max = 2 << bsbits;
+	start = wind = 0;
+	value = last_non_zero = 0;
 
-#define NRL_CHECK_SIZE(req, size, max, chunk_size)	\
-		(req <= (size) || max <= (chunk_size))
+	/* let's choose preallocation window depending on file size */
+	for (i = 0; i < EXT4_MAX_PREALLOC_TABLE; i++) {
+		value = sbi->s_mb_prealloc_table[i];
+		if (value == 0)
+			break;
+		else
+			last_non_zero = value;
 
-	/* first, try to predict filesize */
-	/* XXX: should this table be tunable? */
-	start_off = 0;
-	if (size <= 16 * 1024) {
-		size = 16 * 1024;
-	} else if (size <= 32 * 1024) {
-		size = 32 * 1024;
-	} else if (size <= 64 * 1024) {
-		size = 64 * 1024;
-	} else if (size <= 128 * 1024) {
-		size = 128 * 1024;
-	} else if (size <= 256 * 1024) {
-		size = 256 * 1024;
-	} else if (size <= 512 * 1024) {
-		size = 512 * 1024;
-	} else if (size <= 1024 * 1024) {
-		size = 1024 * 1024;
-	} else if (NRL_CHECK_SIZE(size, 4 * 1024 * 1024, max, 2 * 1024)) {
-		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
-						(21 - bsbits)) << 21;
-		size = 2 * 1024 * 1024;
-	} else if (NRL_CHECK_SIZE(size, 8 * 1024 * 1024, max, 4 * 1024)) {
-		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
-							(22 - bsbits)) << 22;
-		size = 4 * 1024 * 1024;
-	} else if (NRL_CHECK_SIZE(ac->ac_o_ex.fe_len,
-					(8<<20)>>bsbits, max, 8 * 1024)) {
-		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
-							(23 - bsbits)) << 23;
-		size = 8 * 1024 * 1024;
+		if (size <= value) {
+			wind = value;
+			break;
+		}
+	}
+
+	if (wind == 0) {
+		if (last_non_zero != 0) {
+			__u64 tstart, tend;
+			/* file is quite large, we now preallocate with
+		 	* the biggest configured window with regart to
+		 	* logical offset */
+			wind = last_non_zero;
+			tstart = ac->ac_o_ex.fe_logical;
+			do_div(tstart, wind);
+			start = tstart * wind;
+			tend = ac->ac_o_ex.fe_logical + ac->ac_o_ex.fe_len - 1;
+			do_div(tend, wind);
+			tend = tend * wind + wind;
+			size = tend - start;
+		}
 	} else {
-		start_off = (loff_t) ac->ac_o_ex.fe_logical << bsbits;
-		size	  = (loff_t) EXT4_C2B(EXT4_SB(ac->ac_sb),
-					      ac->ac_o_ex.fe_len) << bsbits;
+		size = wind;
 	}
-	size = size >> bsbits;
-	start = start_off >> bsbits;
+
+
+	orig_size = size;
 
 	/* don't cover already allocated blocks in selected range */
 	if (ar->pleft && start <= ar->lleft) {
@@ -3165,7 +3282,6 @@ ext4_mb_normalize_request(struct ext4_al
 			 (unsigned long) ac->ac_o_ex.fe_logical);
 		BUG();
 	}
-	BUG_ON(size <= 0 || size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
 
 	/* now prepare goal request */
 
@@ -4130,11 +4246,19 @@ static void ext4_mb_group_or_file(struct
 
 	/* don't use group allocation for large files */
 	size = max(size, isize);
-	if (size > sbi->s_mb_stream_request) {
+	if ((ac->ac_o_ex.fe_len >= sbi->s_mb_small_req) ||
+	    (size >= sbi->s_mb_large_req)) {
 		ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
 		return;
 	}
 
+	/*
+	 * request is so large that we don't care about
+	 * streaming - it overweights any possible seek
+	 */
+	if (ac->ac_o_ex.fe_len >= sbi->s_mb_large_req)
+		return;
+
 	BUG_ON(ac->ac_lg != NULL);
 	/*
 	 * locality group prealloc space are per cpu. The reason for having
Index: linux-stage/fs/ext4/super.c
===================================================================
--- linux-stage.orig/fs/ext4/super.c
+++ linux-stage/fs/ext4/super.c
@@ -2708,7 +2708,8 @@ EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats
 EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
 EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
 EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
-EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
+EXT4_RW_ATTR_SBI_UI(mb_small_req, s_mb_small_req);
+EXT4_RW_ATTR_SBI_UI(mb_large_req, s_mb_large_req);
 EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
 EXT4_DEPRECATED_ATTR(max_writeback_mb_bump, 128);
 EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
@@ -2734,7 +2735,8 @@ static struct attribute *ext4_attrs[] =
 	ATTR_LIST(mb_max_to_scan),
 	ATTR_LIST(mb_min_to_scan),
 	ATTR_LIST(mb_order2_req),
-	ATTR_LIST(mb_stream_req),
+	ATTR_LIST(mb_small_req),
+	ATTR_LIST(mb_large_req),
 	ATTR_LIST(mb_group_prealloc),
 	ATTR_LIST(max_writeback_mb_bump),
 	ATTR_LIST(extent_max_zeroout_kb),
Index: linux-stage/fs/ext4/inode.c
===================================================================
--- linux-stage.orig/fs/ext4/inode.c
+++ linux-stage/fs/ext4/inode.c
@@ -2457,6 +2457,9 @@ static int ext4_writepages(struct addres
 		ext4_journal_stop(handle);
 	}
 
+	if (wbc->nr_to_write < sbi->s_mb_small_req)
+		wbc->nr_to_write = sbi->s_mb_small_req;
+
 	if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 		range_whole = 1;