Commit 2235219b authored by Badari Pulavarty's avatar Badari Pulavarty Committed by Linus Torvalds

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: default avatarBadari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: default avatarAndreas Dilger <adilger@clusterfs.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8f14137e
...@@ -1099,15 +1099,18 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf) ...@@ -1099,15 +1099,18 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
struct super_block *sb = dentry->d_sb; struct super_block *sb = dentry->d_sb;
struct ext2_sb_info *sbi = EXT2_SB(sb); struct ext2_sb_info *sbi = EXT2_SB(sb);
struct ext2_super_block *es = sbi->s_es; struct ext2_super_block *es = sbi->s_es;
unsigned long overhead;
int i;
u64 fsid; u64 fsid;
if (test_opt (sb, MINIX_DF)) if (test_opt (sb, MINIX_DF))
overhead = 0; sbi->s_overhead_last = 0;
else { 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) ...@@ -1131,17 +1134,22 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
*/ */
overhead += (sbi->s_groups_count * overhead += (sbi->s_groups_count *
(2 + sbi->s_itb_per_group)); (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_type = EXT2_SUPER_MAGIC;
buf->f_bsize = sb->s_blocksize; 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); 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); 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)) if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
buf->f_bavail = 0; buf->f_bavail = 0;
buf->f_files = le32_to_cpu(es->s_inodes_count); buf->f_files = le32_to_cpu(es->s_inodes_count);
buf->f_ffree = ext2_count_free_inodes(sb); 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; buf->f_namelen = EXT2_NAME_LEN;
fsid = le64_to_cpup((void *)es->s_uuid) ^ fsid = le64_to_cpup((void *)es->s_uuid) ^
le64_to_cpup((void *)es->s_uuid + sizeof(u64)); le64_to_cpup((void *)es->s_uuid + sizeof(u64));
......
...@@ -33,6 +33,8 @@ struct ext2_sb_info { ...@@ -33,6 +33,8 @@ struct ext2_sb_info {
unsigned long s_gdb_count; /* Number of group descriptor blocks */ 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_desc_per_block; /* Number of group descriptors per block */
unsigned long s_groups_count; /* Number of groups in the fs */ 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 buffer_head * s_sbh; /* Buffer containing the super block */
struct ext2_super_block * s_es; /* Pointer to the super block in the buffer */ struct ext2_super_block * s_es; /* Pointer to the super block in the buffer */
struct buffer_head ** s_group_desc; struct buffer_head ** s_group_desc;
......
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