From 5e70030d4cf91613530a23b40ad9919bb9ee114f Mon Sep 17 00:00:00 2001 From: Badari Pulavarty Date: Sun, 15 Jul 2007 23:42:00 -0700 Subject: ext4: 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 Signed-off-by: Andreas Dilger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext4/super.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/super.c b/fs/ext4/super.c index adcbfadfcb4..d0d8c76c7ed 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2500,19 +2500,19 @@ static int ext4_statfs (struct dentry * dentry, struct kstatfs * buf) struct super_block *sb = dentry->d_sb; struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_super_block *es = sbi->s_es; - ext4_fsblk_t overhead; - int i; u64 fsid; - if (test_opt (sb, MINIX_DF)) - overhead = 0; - else { - unsigned long ngroups; - ngroups = EXT4_SB(sb)->s_groups_count; + if (test_opt(sb, MINIX_DF)) { + sbi->s_overhead_last = 0; + } else if (sbi->s_blocks_last != le32_to_cpu(es->s_blocks_count)) { + unsigned long ngroups = sbi->s_groups_count, i; + ext4_fsblk_t 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. */ /* @@ -2536,18 +2536,23 @@ static int ext4_statfs (struct dentry * dentry, struct kstatfs * buf) * Every block group has an inode bitmap, a block * bitmap, and an inode table. */ - overhead += (ngroups * (2 + EXT4_SB(sb)->s_itb_per_group)); + overhead += ngroups * (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 = EXT4_SUPER_MAGIC; buf->f_bsize = sb->s_blocksize; - buf->f_blocks = ext4_blocks_count(es) - overhead; + buf->f_blocks = ext4_blocks_count(es) - sbi->s_overhead_last; buf->f_bfree = percpu_counter_sum(&sbi->s_freeblocks_counter); + es->s_free_blocks_count = cpu_to_le32(buf->f_bfree); buf->f_bavail = buf->f_bfree - ext4_r_blocks_count(es); if (buf->f_bfree < ext4_r_blocks_count(es)) buf->f_bavail = 0; buf->f_files = le32_to_cpu(es->s_inodes_count); buf->f_ffree = percpu_counter_sum(&sbi->s_freeinodes_counter); + es->s_free_inodes_count = cpu_to_le32(buf->f_ffree); buf->f_namelen = EXT4_NAME_LEN; fsid = le64_to_cpup((void *)es->s_uuid) ^ le64_to_cpup((void *)es->s_uuid + sizeof(u64)); -- cgit v1.2.3-70-g09d2