[PATCH RFC 3/3] ext4: Notify block device about fallocate(0)-assigned blocks

[Kirill Tkhai <ktkhai@virtuozzo.com>]

Call sb_issue_assign_range() after extent range was allocated
on user request. Hopeful, this helps block device to maintain
its internals in the best way, if this is appliable.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 fs/ext4/ext4.h    |    1 +
 fs/ext4/extents.c |   11 +++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f8578caba40d..fe2263c00c0e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -622,6 +622,7 @@ enum {
 	 * allows jbd2 to avoid submitting data before commit. */
 #define EXT4_GET_BLOCKS_IO_SUBMIT		0x0400
 
+#define EXT4_GET_BLOCKS_SUBMIT_ALLOC		0x0800
 /*
  * The bit position of these flags must not overlap with any of the
  * EXT4_GET_BLOCKS_*.  They are used by ext4_find_extent(),
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 0e8708b77da6..5f4fc660cbb1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4490,6 +4490,13 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 		ar.len = allocated;
 
 got_allocated_blocks:
+	if ((flags & EXT4_GET_BLOCKS_SUBMIT_ALLOC) && sbi->fallocate) {
+		err = sb_issue_assign_range(inode->i_sb, newblock,
+			EXT4_C2B(sbi, allocated_clusters), GFP_NOFS);
+		if (err)
+			goto free_on_err;
+	}
+
 	/* try to insert new extent into found leaf and return */
 	ext4_ext_store_pblock(&newex, newblock + offset);
 	newex.ee_len = cpu_to_le16(ar.len);
@@ -4506,7 +4513,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	if (!err)
 		err = ext4_ext_insert_extent(handle, inode, &path,
 					     &newex, flags);
-
+free_on_err:
 	if (err && free_on_err) {
 		int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ?
 			EXT4_FREE_BLOCKS_NO_QUOT_UPDATE : 0;
@@ -4926,7 +4933,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 	lblk = offset >> blkbits;
 
 	max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
-	flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT;
+	flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT | EXT4_GET_BLOCKS_SUBMIT_ALLOC;
 	if (mode & FALLOC_FL_KEEP_SIZE)
 		flags |= EXT4_GET_BLOCKS_KEEP_SIZE;