Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2235219b7721b8e74de6841e79240936561a2b63
Commit: 2235219b7721b8e74de6841e79240936561a2b63
Parent: 8f14137e284d5733e7be05bd95656f59391b942e
Author: Badari Pulavarty <[EMAIL PROTECTED]>
AuthorDate: Sun Jul 15 23:41:58 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Jul 16 09:05:52 2007 -0700
ext2: statfs speed up
This is a patch that speeds up statfs. It is very simple - the "overhead"
calculation, which takes a huge amount of time for large filesystems, never
changes unless the size of the filesystem itself changes. That means we can
store it in memory and only recalculate if the filesystem has been resized
(almost never).
It also fixes a minor problem that we never update the on-disk superblock
free
blocks/inodes counts until the filesystem is unmounted. While not fatal, we
may as well update that on disk when we have the information, and it makes
things like debugfs and dumpe2fs report a bit more accurate info.
Signed-off-by: Badari Pulavarty <[EMAIL PROTECTED]>
Signed-off-by: Andreas Dilger <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
fs/ext2/super.c | 20 ++++++++++++++------
include/linux/ext2_fs_sb.h | 2 ++
2 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 5de5061..b2efd90 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1099,15 +1099,18 @@ static int ext2_statfs (struct dentry * dentry, struct
kstatfs * buf)
struct super_block *sb = dentry->d_sb;
struct ext2_sb_info *sbi = EXT2_SB(sb);
struct ext2_super_block *es = sbi->s_es;
- unsigned long overhead;
- int i;
u64 fsid;
if (test_opt (sb, MINIX_DF))
- overhead = 0;
- else {
+ sbi->s_overhead_last = 0;
+ else if (sbi->s_blocks_last != le32_to_cpu(es->s_blocks_count)) {
+ unsigned long i, overhead = 0;
+ smp_rmb();
+
/*
- * Compute the overhead (FS structures)
+ * Compute the overhead (FS structures). This is constant
+ * for a given filesystem unless the number of block groups
+ * changes so we cache the previous value until it does.
*/
/*
@@ -1131,17 +1134,22 @@ static int ext2_statfs (struct dentry * dentry, struct
kstatfs * buf)
*/
overhead += (sbi->s_groups_count *
(2 + sbi->s_itb_per_group));
+ sbi->s_overhead_last = overhead;
+ smp_wmb();
+ sbi->s_blocks_last = le32_to_cpu(es->s_blocks_count);
}
buf->f_type = EXT2_SUPER_MAGIC;
buf->f_bsize = sb->s_blocksize;
- buf->f_blocks = le32_to_cpu(es->s_blocks_count) - overhead;
+ buf->f_blocks = le32_to_cpu(es->s_blocks_count) - sbi->s_overhead_last;
buf->f_bfree = ext2_count_free_blocks(sb);
+ es->s_free_blocks_count = cpu_to_le32(buf->f_bfree);
buf->f_bavail = buf->f_bfree - le32_to_cpu(es->s_r_blocks_count);
if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
buf->f_bavail = 0;
buf->f_files = le32_to_cpu(es->s_inodes_count);
buf->f_ffree = ext2_count_free_inodes(sb);
+ es->s_free_inodes_count = cpu_to_le32(buf->f_ffree);
buf->f_namelen = EXT2_NAME_LEN;
fsid = le64_to_cpup((void *)es->s_uuid) ^
le64_to_cpup((void *)es->s_uuid + sizeof(u64));
diff --git a/include/linux/ext2_fs_sb.h b/include/linux/ext2_fs_sb.h
index 4eda0ed..d149f29 100644
--- a/include/linux/ext2_fs_sb.h
+++ b/include/linux/ext2_fs_sb.h
@@ -33,6 +33,8 @@ struct ext2_sb_info {
unsigned long s_gdb_count; /* Number of group descriptor blocks */
unsigned long s_desc_per_block; /* Number of group descriptors per
block */
unsigned long s_groups_count; /* Number of groups in the fs */
+ unsigned long s_overhead_last; /* Last calculated overhead */
+ unsigned long s_blocks_last; /* Last seen block count */
struct buffer_head * s_sbh; /* Buffer containing the super block */
struct ext2_super_block * s_es; /* Pointer to the super block in the
buffer */
struct buffer_head ** s_group_desc;
-
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