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

From: Kirill Tkhai
Date: Tue Dec 10 2019 - 11:57:07 EST


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@xxxxxxxxxxxxx>
---
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;