sysfs: count subdirectories
This patch introduces a subdirectory counter for each sysfs directory.
Without the patch, sysfs_refresh_inode would walk all entries of the directory
to calculate the number of subdirectories.
This patch improves time of "ls -la /sys/block" when there are 10000 block
devices from 9 seconds to 0.19 seconds.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
fs/sysfs/dir.c | 6 ++++++
fs/sysfs/inode.c | 14 +-------------
fs/sysfs/sysfs.h | 2 ++
3 files changed, 9 insertions(+), 13 deletions(-)
Index: linux-3.0-rc7-fast/fs/sysfs/dir.c
===================================================================
--- linux-3.0-rc7-fast.orig/fs/sysfs/dir.c 2011-07-18 19:43:05.000000000 +0200
+++ linux-3.0-rc7-fast/fs/sysfs/dir.c 2011-07-18 19:45:06.000000000 +0200
@@ -47,6 +47,9 @@ static void sysfs_link_sibling(struct sy
BUG_ON(sd->s_sibling);
+ if (sysfs_type(sd) == SYSFS_DIR)
+ parent_sd->s_dir.subdirs++;
+
/* Store directory entries in order by ino. This allows
* readdir to properly restart without having to add a
* cursor into the s_dir.children list.
@@ -73,6 +76,9 @@ static void sysfs_unlink_sibling(struct
{
struct sysfs_dirent **pos;
+ if (sysfs_type(sd) == SYSFS_DIR)
+ sd->s_parent->s_dir.subdirs--;
+
for (pos = &sd->s_parent->s_dir.children; *pos;
pos = &(*pos)->s_sibling) {
if (*pos == sd) {
Index: linux-3.0-rc7-fast/fs/sysfs/inode.c
===================================================================
--- linux-3.0-rc7-fast.orig/fs/sysfs/inode.c 2011-07-18 19:43:33.000000000 +0200
+++ linux-3.0-rc7-fast/fs/sysfs/inode.c 2011-07-18 19:45:50.000000000 +0200
@@ -202,18 +202,6 @@ static inline void set_inode_attr(struct
inode->i_ctime = iattr->ia_ctime;
}
-static int sysfs_count_nlink(struct sysfs_dirent *sd)
-{
- struct sysfs_dirent *child;
- int nr = 0;
-
- for (child = sd->s_dir.children; child; child = child->s_sibling)
- if (sysfs_type(child) == SYSFS_DIR)
- nr++;
-
- return nr + 2;
-}
-
static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
{
struct sysfs_inode_attrs *iattrs = sd->s_iattr;
@@ -230,7 +218,7 @@ static void sysfs_refresh_inode(struct s
}
if (sysfs_type(sd) == SYSFS_DIR)
- inode->i_nlink = sysfs_count_nlink(sd);
+ inode->i_nlink = sd->s_dir.subdirs + 2;
}
int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
Index: linux-3.0-rc7-fast/fs/sysfs/sysfs.h
===================================================================
--- linux-3.0-rc7-fast.orig/fs/sysfs/sysfs.h 2011-07-18 19:42:42.000000000 +0200
+++ linux-3.0-rc7-fast/fs/sysfs/sysfs.h 2011-07-18 19:44:28.000000000 +0200
@@ -19,6 +19,8 @@ struct sysfs_elem_dir {
struct kobject *kobj;
/* children list starts here and goes through sd->s_sibling */
struct sysfs_dirent *children;
+
+ unsigned long subdirs;
};
struct sysfs_elem_symlink {
--
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