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Date: Sat, 5 Jun 2010 23:08:34 -0400
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH] ext4: Clean up s_dirt handling
We don't need to set s_dirt in most of the ext4 code when journaling
is enabled. In ext3/4 some of the summary statistics for # of free
inodes, blocks, and directories are calculated from the per-block
group statistics when the file system is mounted or unmounted. As a
result the superblock doesn't have to be updated, either via the
journal or by setting s_dirt. There are a few exceptions, most
notably when resizing the file system, where the superblock needs to
be modified --- and in that case it should be done as a journalled
operation if possible, and s_dirt set only in no-journal mode.
This patch will optimize out some unneeded disk writes when using ext4
with a journal.
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
fs/ext4/balloc.c | 6 +-----
fs/ext4/ext4.h | 6 ++++++
fs/ext4/ext4_jbd2.c | 16 ++++++++++++++++
fs/ext4/ext4_jbd2.h | 5 +++++
fs/ext4/file.c | 2 +-
fs/ext4/ialloc.c | 4 ++--
fs/ext4/mballoc.c | 4 ++--
fs/ext4/resize.c | 6 ++----
fs/ext4/xattr.c | 3 +--
9 files changed, 36 insertions(+), 16 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 95b7594..bd30799 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -377,14 +377,11 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
ext4_grpblk_t bit;
unsigned int i;
struct ext4_group_desc *desc;
- struct ext4_super_block *es;
- struct ext4_sb_info *sbi;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
int err = 0, ret, blk_free_count;
ext4_grpblk_t blocks_freed;
struct ext4_group_info *grp;
- sbi = EXT4_SB(sb);
- es = sbi->s_es;
ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
@@ -477,7 +474,6 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
if (!err)
err = ret;
- sb->s_dirt = 1;
error_return:
brelse(bitmap_bh);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 19a4de5..8b56b53 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1860,6 +1860,12 @@ static inline void ext4_unlock_group(struct super_block *sb,
spin_unlock(ext4_group_lock_ptr(sb, group));
}
+static inline void ext4_mark_super_dirty(struct super_block *sb)
+{
+ if (EXT4_SB(sb)->s_journal == NULL)
+ sb->s_dirt =1;
+}
+
/*
* Inodes and files operations
*/
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index 53d2764..cfd27b3 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -143,3 +143,19 @@ int __ext4_handle_dirty_metadata(const char *where, handle_t *handle,
}
return err;
}
+
+int __ext4_handle_dirty_super(const char *where, handle_t *handle,
+ struct super_block *sb)
+{
+ struct buffer_head *bh = EXT4_SB(sb)->s_sbh;
+ int err = 0;
+
+ if (ext4_handle_valid(handle)) {
+ err = jbd2_journal_dirty_metadata(handle, bh);
+ if (err)
+ ext4_journal_abort_handle(where, __func__, bh,
+ handle, err);
+ } else
+ sb->s_dirt = 1;
+ return err;
+}
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index dade0c0..8ae8168 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -141,6 +141,9 @@ int __ext4_journal_get_create_access(const char *where,
int __ext4_handle_dirty_metadata(const char *where, handle_t *handle,
struct inode *inode, struct buffer_head *bh);
+int __ext4_handle_dirty_super(const char *where, handle_t *handle,
+ struct super_block *sb);
+
#define ext4_journal_get_undo_access(handle, bh) \
__ext4_journal_get_undo_access(__func__, (handle), (bh))
#define ext4_journal_get_write_access(handle, bh) \
@@ -152,6 +155,8 @@ int __ext4_handle_dirty_metadata(const char *where, handle_t *handle,
__ext4_journal_get_create_access(__func__, (handle), (bh))
#define ext4_handle_dirty_metadata(handle, inode, bh) \
__ext4_handle_dirty_metadata(__func__, (handle), (inode), (bh))
+#define ext4_handle_dirty_super(handle, sb) \
+ __ext4_handle_dirty_super(__func__, (handle), (sb))
handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
int __ext4_journal_stop(const char *where, handle_t *handle);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 5313ae4..bd411c1 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -123,7 +123,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
if (!IS_ERR(cp)) {
memcpy(sbi->s_es->s_last_mounted, cp,
sizeof(sbi->s_es->s_last_mounted));
- sb->s_dirt = 1;
+ ext4_mark_super_dirty(sb);
}
}
return dquot_file_open(inode, filp);
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 25c4b31..ac37750 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -279,7 +279,7 @@ out:
err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
if (!fatal)
fatal = err;
- sb->s_dirt = 1;
+ ext4_mark_super_dirty(sb);
} else
ext4_error(sb, "bit already cleared for inode %lu", ino);
@@ -965,7 +965,7 @@ got:
percpu_counter_dec(&sbi->s_freeinodes_counter);
if (S_ISDIR(mode))
percpu_counter_inc(&sbi->s_dirs_counter);
- sb->s_dirt = 1;
+ ext4_mark_super_dirty(sb);
if (sbi->s_log_groups_per_flex) {
flex_group = ext4_flex_group(sbi, group);
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 12b3bc0..d9d2671 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2812,7 +2812,7 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
err = ext4_handle_dirty_metadata(handle, NULL, gdp_bh);
out_err:
- sb->s_dirt = 1;
+ ext4_mark_super_dirty(sb);
brelse(bitmap_bh);
return err;
}
@@ -4680,7 +4680,7 @@ do_more:
put_bh(bitmap_bh);
goto do_more;
}
- sb->s_dirt = 1;
+ ext4_mark_super_dirty(sb);
error_return:
if (freed)
dquot_free_block(inode, freed);
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 6df797e..27527ae 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -921,8 +921,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
&sbi->s_flex_groups[flex_group].free_inodes);
}
- ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
- sb->s_dirt = 1;
+ ext4_handle_dirty_super(handle, sb);
exit_journal:
mutex_unlock(&sbi->s_resize_lock);
@@ -1045,13 +1044,12 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
goto exit_put;
}
ext4_blocks_count_set(es, o_blocks_count + add);
- ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
- sb->s_dirt = 1;
mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
o_blocks_count + add);
/* We add the blocks to the bitmap and set the group need init bit */
ext4_add_groupblocks(handle, sb, o_blocks_count, add);
+ ext4_handle_dirty_super(handle, sb);
ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
o_blocks_count + add);
if ((err = ext4_journal_stop(handle)))
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 0433800..a6f3142 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -458,8 +458,7 @@ static void ext4_xattr_update_super_block(handle_t *handle,
if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
- sb->s_dirt = 1;
- ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
+ ext4_handle_dirty_super(handle, sb);
}
}
--
1.6.6.1.1.g974db.dirty
--
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