From: Saugata Das <saugata.das@xxxxxxxxxx>
Today, storage devices like eMMC has special features like data tagging
(introduced in MMC-4.5 version) in order to improve performance of some
specific writes. On MMC stack, data tagging is used for all writes which has
REQ_META flag set. On EXT4, however, currently REQ_META is set only for read.
This patch adds the capability to add REQ_META flag during meta data write.
This patch adds new function set_buffer_meta, which is used to set a bit
BH_Meta in the b_state field when meta data and super block is made dirty.
Signed-off-by: Saugata Das <saugata.das@xxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd.bergmann@xxxxxxxxxx>
Changelog v2:
- Removed check for WRITE when setting REQ_META in submit_bh
Changelog v1:
- Introduction of REQ_META during write
---
fs/buffer.c | 3 +++
fs/ext4/ext4_jbd2.c | 4 ++++
fs/ext4/inode.c | 4 +++-
include/linux/buffer_head.h | 2 ++
4 files changed, 12 insertions(+), 1 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 19d8eb7..6eaf492 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2926,6 +2926,9 @@ int submit_bh(int rw, struct buffer_head * bh)
if (test_set_buffer_req(bh) && (rw & WRITE))
clear_buffer_write_io_error(bh);
+ if (buffer_meta(bh))
+ rw |= REQ_META;
+
/*
* from here on down, it's all bio -- do the initial mapping,
* submit_bio -> generic_make_request may further map this bio around
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index aca1790..097c062 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -107,6 +107,8 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line,
{
int err = 0;
+ set_buffer_meta(bh);
+
if (ext4_handle_valid(handle)) {
err = jbd2_journal_dirty_metadata(handle, bh);
if (err) {
@@ -143,6 +145,8 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
struct buffer_head *bh = EXT4_SB(sb)->s_sbh;
int err = 0;
+ set_buffer_meta(bh);
+
if (ext4_handle_valid(handle)) {
err = jbd2_journal_dirty_metadata(handle, bh);
if (err)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 92655fd..105e1d0 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4144,8 +4144,10 @@ int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
err = __ext4_get_inode_loc(inode, &iloc, 0);
if (err)
return err;
- if (wbc->sync_mode == WB_SYNC_ALL)
+ if (wbc->sync_mode == WB_SYNC_ALL) {
+ set_buffer_meta(iloc.bh);
sync_dirty_buffer(iloc.bh);
+ }
if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
"IO error syncing inode");
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 458f497..13bba17 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -34,6 +34,7 @@ enum bh_state_bits {
BH_Write_EIO, /* I/O error on write */
BH_Unwritten, /* Buffer is allocated on disk but not written */
BH_Quiet, /* Buffer Error Prinks to be quiet */
+ BH_Meta, /* Is meta */
BH_PrivateStart,/* not a state bit, but the first bit available
* for private allocation by other entities
@@ -124,6 +125,7 @@ BUFFER_FNS(Delay, delay)
BUFFER_FNS(Boundary, boundary)
BUFFER_FNS(Write_EIO, write_io_error)
BUFFER_FNS(Unwritten, unwritten)
+BUFFER_FNS(Meta, meta)
#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
#define touch_buffer(bh) mark_page_accessed(bh->b_page)
--
1.7.4.3
--
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