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Subject[patch 5/6] vfs: optimization to /proc/<pid>/mountinfo patch
From: Ram Pai <linuxram@us.ibm.com>

1) reports deleted inode in dentry_path() consistent with that in __d_path()
2) modified __d_path() to use prepend(), reducing the size of __d_path()
3) moved all the functionality that reports mount information in /proc under
CONFIG_PROC_FS.

Code compile tested only with and without CONFIG_PROC_FS.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
fs/dcache.c | 63 ++++++++++++++++++++---------------------------
fs/namespace.c | 4 ++
fs/pnode.c | 10 ++++---
fs/pnode.h | 4 ++
fs/seq_file.c | 3 +-
include/linux/dcache.h | 3 ++
include/linux/seq_file.h | 3 ++
7 files changed, 47 insertions(+), 43 deletions(-)

Index: linux/fs/dcache.c
===================================================================
--- linux.orig/fs/dcache.c 2008-03-13 20:45:15.000000000 +0100
+++ linux/fs/dcache.c 2008-03-13 20:45:52.000000000 +0100
@@ -1747,6 +1747,17 @@ shouldnt_be_hashed:
goto shouldnt_be_hashed;
}

+static int prepend(char **buffer, int *buflen, const char *str,
+ int namelen)
+{
+ *buflen -= namelen;
+ if (*buflen < 0)
+ return -ENAMETOOLONG;
+ *buffer -= namelen;
+ memcpy(*buffer, str, namelen);
+ return 0;
+}
+
/**
* d_path - return the path of a dentry
* @dentry: dentry to report
@@ -1768,17 +1779,11 @@ static char *__d_path(struct dentry *den
{
char * end = buffer+buflen;
char * retval;
- int namelen;

- *--end = '\0';
- buflen--;
- if (!IS_ROOT(dentry) && d_unhashed(dentry)) {
- buflen -= 10;
- end -= 10;
- if (buflen < 0)
+ prepend(&end, &buflen, "\0", 1);
+ if (!IS_ROOT(dentry) && d_unhashed(dentry) &&
+ (prepend(&end, &buflen, " (deleted)", 10) != 0))
goto Elong;
- memcpy(end, " (deleted)", 10);
- }

if (buflen < 1)
goto Elong;
@@ -1805,13 +1810,10 @@ static char *__d_path(struct dentry *den
}
parent = dentry->d_parent;
prefetch(parent);
- namelen = dentry->d_name.len;
- buflen -= namelen + 1;
- if (buflen < 0)
+ if ((prepend(&end, &buflen, dentry->d_name.name,
+ dentry->d_name.len) != 0) ||
+ (prepend(&end, &buflen, "/", 1) != 0))
goto Elong;
- end -= namelen;
- memcpy(end, dentry->d_name.name, namelen);
- *--end = '/';
retval = end;
dentry = parent;
}
@@ -1819,12 +1821,10 @@ static char *__d_path(struct dentry *den
return retval;

global_root:
- namelen = dentry->d_name.len;
- buflen -= namelen;
- if (buflen < 0)
+ retval += 1; /* hit the slash */
+ if (prepend(&retval, &buflen, dentry->d_name.name,
+ dentry->d_name.len) != 0)
goto Elong;
- retval -= namelen-1; /* hit the slash */
- memcpy(retval, dentry->d_name.name, namelen);
return retval;
Elong:
return ERR_PTR(-ENAMETOOLONG);
@@ -1890,17 +1890,8 @@ char *dynamic_dname(struct dentry *dentr
return memcpy(buffer, temp, sz);
}

-static int prepend(char **buffer, int *buflen, const char *str,
- int namelen)
-{
- *buflen -= namelen;
- if (*buflen < 0)
- return 1;
- *buffer -= namelen;
- memcpy(*buffer, str, namelen);
- return 0;
-}

+#ifdef CONFIG_PROC_FS
/*
* Write full pathname from the root of the filesystem into the buffer.
*/
@@ -1911,10 +1902,9 @@ char *dentry_path(struct dentry *dentry,

spin_lock(&dcache_lock);
prepend(&end, &buflen, "\0", 1);
- if (!IS_ROOT(dentry) && d_unhashed(dentry)) {
- if (prepend(&end, &buflen, "//deleted", 9))
+ if (!IS_ROOT(dentry) && d_unhashed(dentry) &&
+ (prepend(&end, &buflen, " (deleted)", 10) != 0))
goto Elong;
- }
if (buflen < 1)
goto Elong;
/* Get '/' right */
@@ -1929,9 +1919,9 @@ char *dentry_path(struct dentry *dentry,
parent = dentry->d_parent;
prefetch(parent);

- if (prepend(&end, &buflen, dentry->d_name.name,
- dentry->d_name.len) ||
- prepend(&end, &buflen, "/", 1))
+ if ((prepend(&end, &buflen, dentry->d_name.name,
+ dentry->d_name.len) != 0) ||
+ (prepend(&end, &buflen, "/", 1) != 0))
goto Elong;

retval = end;
@@ -1943,6 +1933,7 @@ Elong:
spin_unlock(&dcache_lock);
return ERR_PTR(-ENAMETOOLONG);
}
+#endif /* CONFIG_PROC_FS */

/*
* NOTE! The user-level library version returns a
Index: linux/fs/namespace.c
===================================================================
--- linux.orig/fs/namespace.c 2008-03-13 20:45:51.000000000 +0100
+++ linux/fs/namespace.c 2008-03-13 20:45:52.000000000 +0100
@@ -679,6 +679,7 @@ void save_mount_options(struct super_blo
}
EXPORT_SYMBOL(save_mount_options);

+#ifdef CONFIG_PROC_FS
/* iterator */
static void *m_start(struct seq_file *m, loff_t *pos)
{
@@ -808,7 +809,7 @@ static int show_mountinfo(struct seq_fil
if (IS_MNT_SHARED(mnt))
seq_putc(m, ',');

- seq_printf(m, "slave:%i", get_master_id(mnt));
+ seq_printf(m, "slave:%i", get_master_group_id(mnt));
if (dominator_id != -1)
seq_printf(m, ":%i", dominator_id);
}
@@ -866,6 +867,7 @@ const struct seq_operations mountstats_o
.stop = m_stop,
.show = show_vfsstat,
};
+#endif /* CONFIG_PROC_FS */

/**
* may_umount_tree - check if a mount tree is busy
Index: linux/fs/seq_file.c
===================================================================
--- linux.orig/fs/seq_file.c 2008-03-13 20:45:15.000000000 +0100
+++ linux/fs/seq_file.c 2008-03-13 20:45:52.000000000 +0100
@@ -391,6 +391,7 @@ int seq_path(struct seq_file *m, struct
}
EXPORT_SYMBOL(seq_path);

+#ifdef CONFIG_PROC_FS
/*
* returns the path of the 'dentry' from the root of its filesystem.
*/
@@ -411,7 +412,7 @@ int seq_dentry(struct seq_file *m, struc
m->count = m->size;
return -1;
}
-EXPORT_SYMBOL(seq_dentry);
+#endif /* CONFIG_PROC_FS */

static void *single_start(struct seq_file *p, loff_t *pos)
{
Index: linux/include/linux/dcache.h
===================================================================
--- linux.orig/include/linux/dcache.h 2008-03-13 20:45:15.000000000 +0100
+++ linux/include/linux/dcache.h 2008-03-13 20:45:52.000000000 +0100
@@ -303,7 +303,10 @@ extern int d_validate(struct dentry *, s
extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);

extern char *d_path(struct path *, char *, int);
+
+#ifdef CONFIG_PROC_FS
extern char *dentry_path(struct dentry *, char *, int);
+#endif /* CONFIG_PROC_FS */

/* Allocation counts.. */

Index: linux/include/linux/seq_file.h
===================================================================
--- linux.orig/include/linux/seq_file.h 2008-03-13 20:45:15.000000000 +0100
+++ linux/include/linux/seq_file.h 2008-03-13 20:45:52.000000000 +0100
@@ -44,7 +44,10 @@ int seq_printf(struct seq_file *, const
__attribute__ ((format (printf,2,3)));

int seq_path(struct seq_file *, struct path *, char *);
+
+#ifdef CONFIG_PROC_FS
int seq_dentry(struct seq_file *, struct dentry *, char *);
+#endif /* CONFIG_PROC_FS */

int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
int single_release(struct inode *, struct file *);
Index: linux/fs/pnode.c
===================================================================
--- linux.orig/fs/pnode.c 2008-03-13 20:45:51.000000000 +0100
+++ linux/fs/pnode.c 2008-03-13 20:45:52.000000000 +0100
@@ -72,12 +72,13 @@ void make_mnt_peer(struct vfsmount *old,
__set_mnt_shared(mnt);
}

+#ifdef CONFIG_PROC_FS
int get_peer_group_id(struct vfsmount *mnt)
{
return mnt->mnt_pgid;
}

-int get_master_id(struct vfsmount *mnt)
+int get_master_group_id(struct vfsmount *mnt)
{
int id;

@@ -119,6 +120,7 @@ int get_dominator_id_same_ns(struct vfsm

return id;
}
+#endif

static int do_make_slave(struct vfsmount *mnt)
{
@@ -138,13 +140,13 @@ static int do_make_slave(struct vfsmount
if (peer_mnt == mnt)
peer_mnt = NULL;
}
- if (!list_empty(&mnt->mnt_share))
- list_del_init(&mnt->mnt_share);
- else if (IS_MNT_SHARED(mnt)) {
+
+ if (IS_MNT_SHARED(mnt) && list_empty(&mnt->mnt_share)) {
spin_lock(&mnt_pgid_lock);
ida_remove(&mnt_pgid_ida, mnt->mnt_pgid);
spin_unlock(&mnt_pgid_lock);
}
+ list_del_init(&mnt->mnt_share);

if (peer_mnt)
master = peer_mnt;
Index: linux/fs/pnode.h
===================================================================
--- linux.orig/fs/pnode.h 2008-03-13 20:45:51.000000000 +0100
+++ linux/fs/pnode.h 2008-03-13 20:45:52.000000000 +0100
@@ -31,7 +31,9 @@ int propagate_mnt(struct vfsmount *, str
struct list_head *);
int propagate_umount(struct list_head *);
int propagate_mount_busy(struct vfsmount *, int);
+
int get_peer_group_id(struct vfsmount *);
-int get_master_id(struct vfsmount *);
+int get_master_group_id(struct vfsmount *);
int get_dominator_id_same_ns(struct vfsmount *);
+
#endif /* _LINUX_PNODE_H */
--


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