Re: [rfc] object collection tracing (was: [PATCH 5/5] proc: exportmore page flags in /proc/kpageflags)

From: Wu Fengguang
Date: Sun May 17 2009 - 09:38:40 EST

On Tue, May 12, 2009 at 09:01:12PM +0800, Frederic Weisbecker wrote:
> On Tue, Apr 28, 2009 at 09:31:08PM +0800, Wu Fengguang wrote:
> > On Tue, Apr 28, 2009 at 08:17:51PM +0800, Ingo Molnar wrote:
> >
> > There are two possible challenges for the conversion:
> >
> > - One trick it does is to select different lists to traverse on
> > different filter options. Will this be possible in the object
> > tracing framework?
>
> Yeah, I guess.

Great.

>
> > - The file name lookup(last field) is the performance killer. Is it
> > possible to skip the file name lookup when the filter failed on the
> > leading fields?
>
> objects collection lays on trace events where filters basically ignore
> a whole entry in case of non-matching. Not sure if we can easily only
> ignore one field.
>
> But I guess we can do something about the performances...

OK, but it's not as important as the previous requirement, so it could
be the last thing to work on :)

> Could you send us the (sob'ed) patch you made which implements this.
> I could try to adapt it to object collection.

Attached for your reference. Be aware that I still have plans to
change it in non trivial way, and there are ongoing works by Nick(on
inode_lock) and Jens(on s_dirty) that can create merge conflicts.
So basically it is not a right time to do the adaption.

However we can still do something to polish up the page object
collection under /debug/tracing/objects/mm/pages/. For example,
the timestamps and function name could be removed from the following
list :)

# tracer: nop
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
<...>-3743 [001] 3035.649769: dump_pages: pfn=1 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176403: dump_pages: pfn=1 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176407: dump_pages: pfn=2 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176408: dump_pages: pfn=3 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176409: dump_pages: pfn=4 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176409: dump_pages: pfn=5 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176410: dump_pages: pfn=6 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176410: dump_pages: pfn=7 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176411: dump_pages: pfn=8 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176411: dump_pages: pfn=9 flags=400 count=1 mapcount=0 index=0
<...>-3743 [001] 3044.176412: dump_pages: pfn=10 flags=400 count=1 mapcount=0 index=0

Thanks,
Fengguang
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -27,6 +27,7 @@ extern unsigned long max_mapnr;
extern unsigned long num_physpages;
extern void * high_memory;
extern int page_cluster;
+extern char * const zone_names[];

#ifdef CONFIG_SYSCTL
extern int sysctl_legacy_va_layout;
--- linux-2.6.orig/mm/page_alloc.c
+++ linux-2.6/mm/page_alloc.c
@@ -104,7 +104,7 @@ int sysctl_lowmem_reserve_ratio[MAX_NR_Z

EXPORT_SYMBOL(totalram_pages);

-static char * const zone_names[MAX_NR_ZONES] = {
+char * const zone_names[MAX_NR_ZONES] = {
#ifdef CONFIG_ZONE_DMA
"DMA",
#endif
--- linux-2.6.orig/fs/dcache.c
+++ linux-2.6/fs/dcache.c
@@ -1925,7 +1925,10 @@ char *__d_path(const struct path *path,

if (dentry == root->dentry && vfsmnt == root->mnt)
break;
- if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
+ if (unlikely(!vfsmnt)) {
+ if (IS_ROOT(dentry))
+ break;
+ } else if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
/* Global root? */
if (vfsmnt->mnt_parent == vfsmnt) {
goto global_root;
--- linux-2.6.orig/lib/radix-tree.c
+++ linux-2.6/lib/radix-tree.c
@@ -564,7 +564,6 @@ out:
}
EXPORT_SYMBOL(radix_tree_tag_clear);

-#ifndef __KERNEL__ /* Only the test harness uses this at present */
/**
* radix_tree_tag_get - get a tag on a radix tree node
* @root: radix tree root
@@ -627,7 +626,6 @@ int radix_tree_tag_get(struct radix_tree
}
}
EXPORT_SYMBOL(radix_tree_tag_get);
-#endif

/**
* radix_tree_next_hole - find the next hole (not-present entry)
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -84,6 +84,10 @@ static struct hlist_head *inode_hashtabl
*/
DEFINE_SPINLOCK(inode_lock);

+EXPORT_SYMBOL(inode_in_use);
+EXPORT_SYMBOL(inode_unused);
+EXPORT_SYMBOL(inode_lock);
+
/*
* iprune_mutex provides exclusion between the kswapd or try_to_free_pages
* icache shrinking path, and the umount path. Without this exclusion,
@@ -110,6 +114,13 @@ static void wake_up_inode(struct inode *
wake_up_bit(&inode->i_state, __I_LOCK);
}

+static inline void inode_created_by(struct inode *inode, struct task_struct *task)
+{
+#ifdef CONFIG_PROC_FILECACHE_EXTRAS
+ memcpy(inode->i_comm, task->comm, sizeof(task->comm));
+#endif
+}
+
/**
* inode_init_always - perform inode structure intialisation
* @sb: superblock inode belongs to
@@ -147,7 +158,7 @@ struct inode *inode_init_always(struct s
inode->i_bdev = NULL;
inode->i_cdev = NULL;
inode->i_rdev = 0;
- inode->dirtied_when = 0;
+ inode->dirtied_when = jiffies;

if (security_inode_alloc(inode))
goto out_free_inode;
@@ -188,6 +199,7 @@ struct inode *inode_init_always(struct s
}
inode->i_private = NULL;
inode->i_mapping = mapping;
+ inode_created_by(inode, current);

return inode;

@@ -276,6 +288,8 @@ void __iget(struct inode *inode)
inodes_stat.nr_unused--;
}

+EXPORT_SYMBOL(__iget);
+
/**
* clear_inode - clear an inode
* @inode: inode to clear
@@ -1459,6 +1473,16 @@ static void __wait_on_freeing_inode(stru
spin_lock(&inode_lock);
}

+
+struct hlist_head * get_inode_hash_budget(unsigned long index)
+{
+ if (index >= (1 << i_hash_shift))
+ return NULL;
+
+ return inode_hashtable + index;
+}
+EXPORT_SYMBOL_GPL(get_inode_hash_budget);
+
static __initdata unsigned long ihash_entries;
static int __init set_ihash_entries(char *str)
{
--- linux-2.6.orig/fs/super.c
+++ linux-2.6/fs/super.c
@@ -46,6 +46,9 @@
LIST_HEAD(super_blocks);
DEFINE_SPINLOCK(sb_lock);

+EXPORT_SYMBOL(super_blocks);
+EXPORT_SYMBOL(sb_lock);
+
/**
* alloc_super - create new superblock
* @type: filesystem type superblock should belong to
--- linux-2.6.orig/mm/vmscan.c
+++ linux-2.6/mm/vmscan.c
@@ -262,6 +262,7 @@ unsigned long shrink_slab(unsigned long
up_read(&shrinker_rwsem);
return ret;
}
+EXPORT_SYMBOL(shrink_slab);

/* Called without lock on whether page is mapped, so answer is unstable */
static inline int page_mapping_inuse(struct page *page)
--- linux-2.6.orig/mm/swap_state.c
+++ linux-2.6/mm/swap_state.c
@@ -45,6 +45,7 @@ struct address_space swapper_space = {
.i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
.backing_dev_info = &swap_backing_dev_info,
};
+EXPORT_SYMBOL_GPL(swapper_space);

#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)

--- linux-2.6.orig/Documentation/filesystems/proc.txt
+++ linux-2.6/Documentation/filesystems/proc.txt
@@ -260,6 +260,7 @@ Table 1-4: Kernel info in /proc
driver Various drivers grouped here, currently rtc (2.4)
execdomains Execdomains, related to security (2.4)
fb Frame Buffer devices (2.4)
+ filecache Query/drop in-memory file cache
fs File system parameters, currently nfs/exports (2.4)
ide Directory containing info about the IDE subsystem
interrupts Interrupt usage
@@ -450,6 +451,88 @@ varies by architecture and compile optio

> cat /proc/meminfo

+..............................................................................
+
+filecache:
+
+Provides access to the in-memory file cache.
+
+To list an index of all cached files:
+
+ echo ls > /proc/filecache
+ cat /proc/filecache
+
+The output looks like:
+
+ # filecache 1.0
+ # ino size cached cached% state refcnt dev file
+ 1026334 91 92 100 -- 66 03:02(hda2) /lib/ld-2.3.6.so
+ 233608 1242 972 78 -- 66 03:02(hda2) /lib/tls/libc-2.3.6.so
+ 65203 651 476 73 -- 1 03:02(hda2) /bin/bash
+ 1026445 261 160 61 -- 10 03:02(hda2) /lib/libncurses.so.5.5
+ 235427 10 12 100 -- 44 03:02(hda2) /lib/tls/libdl-2.3.6.so
+
+FIELD INTRO
+---------------------------------------------------------------------------
+ino inode number
+size inode size in KB
+cached cached size in KB
+cached% percent of file data cached
+state1 '-' clean; 'd' metadata dirty; 'D' data dirty
+state2 '-' unlocked; 'L' locked, normally indicates file being written out
+refcnt file reference count, it's an in-kernel one, not exactly open count
+dev major:minor numbers in hex, followed by a descriptive device name
+file file path _inside_ the filesystem. There are several special names:
+ '(noname)': the file name is not available
+ '(03:02)': the file is a block device file of major:minor
+ '...(deleted)': the named file has been deleted from the disk
+
+To list the cached pages of a perticular file:
+
+ echo /bin/bash > /proc/filecache
+ cat /proc/filecache
+
+ # file /bin/bash
+ # flags R:referenced A:active U:uptodate D:dirty W:writeback M:mmap
+ # idx len state refcnt
+ 0 36 RAU__M 3
+ 36 1 RAU__M 2
+ 37 8 RAU__M 3
+ 45 2 RAU___ 1
+ 47 6 RAU__M 3
+ 53 3 RAU__M 2
+ 56 2 RAU__M 3
+
+FIELD INTRO
+----------------------------------------------------------------------------
+idx page index
+len number of pages which are cached and share the same state
+state page state of the flags listed in line two
+refcnt page reference count
+
+Careful users may notice that the file name to be queried is remembered between
+commands. Internally, the module has a global variable to store the file name
+parameter, so that it can be inherited by newly opened /proc/filecache file.
+However it can lead to interference for multiple queriers. The solution here
+is to obey a rule: only root can interactively change the file name parameter;
+normal users must go for scripts to access the interface. Scripts should do it
+by following the code example below:
+
+ filecache = open("/proc/filecache", "rw");
+ # avoid polluting the global parameter filename
+ filecache.write("set private");
+
+To instruct the kernel to drop clean caches, dentries and inodes from memory,
+causing that memory to become free:
+
+ # drop clean file data cache (i.e. file backed pagecache)
+ echo drop pagecache > /proc/filecache
+
+ # drop clean file metadata cache (i.e. dentries and inodes)
+ echo drop slabcache > /proc/filecache
+
+Note that the drop commands are non-destructive operations and dirty objects
+are not freeable, the user should run `sync' first.

MemTotal: 16344972 kB
MemFree: 13634064 kB
--- /dev/null
+++ linux-2.6/fs/proc/filecache.c
@@ -0,0 +1,1045 @@
+/*
+ * fs/proc/filecache.c
+ *
+ * Copyright (C) 2006, 2007 Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/radix-tree.h>
+#include <linux/page-flags.h>
+#include <linux/pagevec.h>
+#include <linux/pagemap.h>
+#include <linux/vmalloc.h>
+#include <linux/writeback.h>
+#include <linux/buffer_head.h>
+#include <linux/parser.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/file.h>
+#include <linux/namei.h>
+#include <linux/module.h>
+#include <asm/uaccess.h>
+
+/*
+ * Increase minor version when new columns are added;
+ * Increase major version when existing columns are changed.
+ */
+#define FILECACHE_VERSION "1.0"
+
+/* Internal buffer sizes. The larger the more effcient. */
+#define SBUF_SIZE (128<<10)
+#define IWIN_PAGE_ORDER 3
+#define IWIN_SIZE ((PAGE_SIZE<<IWIN_PAGE_ORDER) / sizeof(struct inode *))
+
+/*
+ * Session management.
+ *
+ * Each opened /proc/filecache file is assiocated with a session object.
+ * Also there is a global_session that maintains status across open()/close()
+ * (i.e. the lifetime of an opened file), so that a casual user can query the
+ * filecache via _multiple_ simple shell commands like
+ * 'echo cat /bin/bash > /proc/filecache; cat /proc/filecache'.
+ *
+ * session.query_file is the file whose cache info is to be queried.
+ * Its value determines what we get on read():
+ * - NULL: ii_*() called to show the inode index
+ * - filp: pg_*() called to show the page groups of a filp
+ *
+ * session.query_file is
+ * - cloned from global_session.query_file on open();
+ * - updated on write("cat filename");
+ * note that the new file will also be saved in global_session.query_file if
+ * session.private_session is false.
+ */
+
+struct session {
+ /* options */
+ int private_session;
+ unsigned long ls_options;
+ dev_t ls_dev;
+
+ /* parameters */
+ struct file *query_file;
+
+ /* seqfile pos */
+ pgoff_t start_offset;
+ pgoff_t next_offset;
+
+ /* inode at last pos */
+ struct {
+ unsigned long pos;
+ unsigned long state;
+ struct inode *inode;
+ struct inode *pinned_inode;
+ } ipos;
+
+ /* inode window */
+ struct {
+ unsigned long cursor;
+ unsigned long origin;
+ unsigned long size;
+ struct inode **inodes;
+ } iwin;
+};
+
+static struct session global_session;
+
+/*
+ * Session address is stored in proc_file->f_ra.start:
+ * we assume that there will be no readahead for proc_file.
+ */
+static struct session *get_session(struct file *proc_file)
+{
+ return (struct session *)proc_file->f_ra.start;
+}
+
+static void set_session(struct file *proc_file, struct session *s)
+{
+ BUG_ON(proc_file->f_ra.start);
+ proc_file->f_ra.start = (unsigned long)s;
+}
+
+static void update_global_file(struct session *s)
+{
+ if (s->private_session)
+ return;
+
+ if (global_session.query_file)
+ fput(global_session.query_file);
+
+ global_session.query_file = s->query_file;
+
+ if (global_session.query_file)
+ get_file(global_session.query_file);
+}
+
+/*
+ * Cases of the name:
+ * 1) NULL (new session)
+ * s->query_file = global_session.query_file = 0;
+ * 2) "" (ls/la)
+ * s->query_file = global_session.query_file;
+ * 3) a regular file name (cat newfile)
+ * s->query_file = global_session.query_file = newfile;
+ */
+static int session_update_file(struct session *s, char *name)
+{
+ static DEFINE_MUTEX(mutex); /* protects global_session.query_file */
+ int err = 0;
+
+ mutex_lock(&mutex);
+
+ /*
+ * We are to quit, or to list the cached files.
+ * Reset *.query_file.
+ */
+ if (!name) {
+ if (s->query_file) {
+ fput(s->query_file);
+ s->query_file = NULL;
+ }
+ update_global_file(s);
+ goto out;
+ }
+
+ /*
+ * This is a new session.
+ * Inherit options/parameters from global ones.
+ */
+ if (name[0] == '\0') {
+ *s = global_session;
+ if (s->query_file)
+ get_file(s->query_file);
+ goto out;
+ }
+
+ /*
+ * Open the named file.
+ */
+ if (s->query_file)
+ fput(s->query_file);
+ s->query_file = filp_open(name, O_RDONLY|O_LARGEFILE, 0);
+ if (IS_ERR(s->query_file)) {
+ err = PTR_ERR(s->query_file);
+ s->query_file = NULL;
+ } else
+ update_global_file(s);
+
+out:
+ mutex_unlock(&mutex);
+
+ return err;
+}
+
+static struct session *session_create(void)
+{
+ struct session *s;
+ int err = 0;
+
+ s = kmalloc(sizeof(*s), GFP_KERNEL);
+ if (s)
+ err = session_update_file(s, "");
+ else
+ err = -ENOMEM;
+
+ return err ? ERR_PTR(err) : s;
+}
+
+static void session_release(struct session *s)
+{
+ if (s->ipos.pinned_inode)
+ iput(s->ipos.pinned_inode);
+ if (s->query_file)
+ fput(s->query_file);
+ kfree(s);
+}
+
+
+/*
+ * Listing of cached files.
+ *
+ * Usage:
+ * echo > /proc/filecache # enter listing mode
+ * cat /proc/filecache # get the file listing
+ */
+
+/* code style borrowed from ib_srp.c */
+enum {
+ LS_OPT_ERR = 0,
+ LS_OPT_DIRTY = 1 << 0,
+ LS_OPT_CLEAN = 1 << 1,
+ LS_OPT_INUSE = 1 << 2,
+ LS_OPT_EMPTY = 1 << 3,
+ LS_OPT_ALL = 1 << 4,
+ LS_OPT_DEV = 1 << 5,
+};
+
+static match_table_t ls_opt_tokens = {
+ { LS_OPT_DIRTY, "dirty" },
+ { LS_OPT_CLEAN, "clean" },
+ { LS_OPT_INUSE, "inuse" },
+ { LS_OPT_EMPTY, "empty" },
+ { LS_OPT_ALL, "all" },
+ { LS_OPT_DEV, "dev=%s" },
+ { LS_OPT_ERR, NULL }
+};
+
+static int ls_parse_options(const char *buf, struct session *s)
+{
+ substring_t args[MAX_OPT_ARGS];
+ char *options, *sep_opt;
+ char *p;
+ int token;
+ int ret = 0;
+
+ if (!buf)
+ return 0;
+ options = kstrdup(buf, GFP_KERNEL);
+ if (!options)
+ return -ENOMEM;
+
+ s->ls_options = 0;
+ sep_opt = options;
+ while ((p = strsep(&sep_opt, " ")) != NULL) {
+ if (!*p)
+ continue;
+
+ token = match_token(p, ls_opt_tokens, args);
+
+ switch (token) {
+ case LS_OPT_DIRTY:
+ case LS_OPT_CLEAN:
+ case LS_OPT_INUSE:
+ case LS_OPT_EMPTY:
+ case LS_OPT_ALL:
+ s->ls_options |= token;
+ break;
+ case LS_OPT_DEV:
+ p = match_strdup(args);
+ if (!p) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ if (*p == '/') {
+ struct kstat stat;
+ struct nameidata nd;
+ ret = path_lookup(p, LOOKUP_FOLLOW, &nd);
+ if (!ret)
+ ret = vfs_getattr(nd.path.mnt,
+ nd.path.dentry, &stat);
+ if (!ret)
+ s->ls_dev = stat.rdev;
+ } else
+ s->ls_dev = simple_strtoul(p, NULL, 0);
+ /* printk("%lx %s\n", (long)s->ls_dev, p); */
+ kfree(p);
+ break;
+
+ default:
+ printk(KERN_WARNING "unknown parameter or missing value "
+ "'%s' in ls command\n", p);
+ ret = -EINVAL;
+ goto out;
+ }
+ }
+
+out:
+ kfree(options);
+ return ret;
+}
+
+/*
+ * Add possible filters here.
+ * No permission check: we cannot verify the path's permission anyway.
+ * We simply demand root previledge for accessing /proc/filecache.
+ */
+static int may_show_inode(struct session *s, struct inode *inode)
+{
+ if (!atomic_read(&inode->i_count))
+ return 0;
+ if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
+ return 0;
+ if (!inode->i_mapping)
+ return 0;
+
+ if (s->ls_dev && s->ls_dev != inode->i_sb->s_dev)
+ return 0;
+
+ if (s->ls_options & LS_OPT_ALL)
+ return 1;
+
+ if (!(s->ls_options & LS_OPT_EMPTY) && !inode->i_mapping->nrpages)
+ return 0;
+
+ if ((s->ls_options & LS_OPT_DIRTY) && !(inode->i_state & I_DIRTY))
+ return 0;
+
+ if ((s->ls_options & LS_OPT_CLEAN) && (inode->i_state & I_DIRTY))
+ return 0;
+
+ if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+ S_ISLNK(inode->i_mode) || S_ISBLK(inode->i_mode)))
+ return 0;
+
+ return 1;
+}
+
+/*
+ * Full: there are more data following.
+ */
+static int iwin_full(struct session *s)
+{
+ return !s->iwin.cursor ||
+ s->iwin.cursor > s->iwin.origin + s->iwin.size;
+}
+
+static int iwin_push(struct session *s, struct inode *inode)
+{
+ if (!may_show_inode(s, inode))
+ return 0;
+
+ s->iwin.cursor++;
+
+ if (s->iwin.size >= IWIN_SIZE)
+ return 1;
+
+ if (s->iwin.cursor > s->iwin.origin)
+ s->iwin.inodes[s->iwin.size++] = inode;
+ return 0;
+}
+
+/*
+ * Travease the inode lists in order - newest first.
+ * And fill @s->iwin.inodes with inodes positioned in [@pos, @pos+IWIN_SIZE).
+ */
+static int iwin_fill(struct session *s, unsigned long pos)
+{
+ struct inode *inode;
+ struct super_block *sb;
+
+ s->iwin.origin = pos;
+ s->iwin.cursor = 0;
+ s->iwin.size = 0;
+
+ /*
+ * We have a cursor inode, clean and expected to be unchanged.
+ */
+ if (s->ipos.inode && pos >= s->ipos.pos &&
+ !(s->ipos.state & I_DIRTY) &&
+ s->ipos.state == s->ipos.inode->i_state) {
+ inode = s->ipos.inode;
+ s->iwin.cursor = s->ipos.pos;
+ goto continue_from_saved;
+ }
+
+ if (s->ls_options & LS_OPT_CLEAN)
+ goto clean_inodes;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (s->ls_dev && s->ls_dev != sb->s_dev)
+ continue;
+
+ list_for_each_entry(inode, &sb->s_dirty, i_list) {
+ if (iwin_push(s, inode))
+ goto out_full_unlock;
+ }
+ list_for_each_entry(inode, &sb->s_io, i_list) {
+ if (iwin_push(s, inode))
+ goto out_full_unlock;
+ }
+ }
+ spin_unlock(&sb_lock);
+
+clean_inodes:
+ list_for_each_entry(inode, &inode_in_use, i_list) {
+ if (iwin_push(s, inode))
+ goto out_full;
+continue_from_saved:
+ ;
+ }
+
+ if (s->ls_options & LS_OPT_INUSE)
+ return 0;
+
+ list_for_each_entry(inode, &inode_unused, i_list) {
+ if (iwin_push(s, inode))
+ goto out_full;
+ }
+
+ return 0;
+
+out_full_unlock:
+ spin_unlock(&sb_lock);
+out_full:
+ return 1;
+}
+
+static struct inode *iwin_inode(struct session *s, unsigned long pos)
+{
+ if ((iwin_full(s) && pos >= s->iwin.origin + s->iwin.size)
+ || pos < s->iwin.origin)
+ iwin_fill(s, pos);
+
+ if (pos >= s->iwin.cursor)
+ return NULL;
+
+ s->ipos.pos = pos;
+ s->ipos.inode = s->iwin.inodes[pos - s->iwin.origin];
+ BUG_ON(!s->ipos.inode);
+ return s->ipos.inode;
+}
+
+static void show_inode(struct seq_file *m, struct inode *inode)
+{
+ char state[] = "--"; /* dirty, locked */
+ struct dentry *dentry;
+ loff_t size = i_size_read(inode);
+ unsigned long nrpages;
+ int percent;
+ int refcnt;
+ int shift;
+
+ if (!size)
+ size++;
+
+ if (inode->i_mapping)
+ nrpages = inode->i_mapping->nrpages;
+ else {
+ nrpages = 0;
+ WARN_ON(1);
+ }
+
+ for (shift = 0; (size >> shift) > ULONG_MAX / 128; shift += 12)
+ ;
+ percent = min(100UL, (((100 * nrpages) >> shift) << PAGE_CACHE_SHIFT) /
+ (unsigned long)(size >> shift));
+
+ if (inode->i_state & (I_DIRTY_DATASYNC|I_DIRTY_PAGES))
+ state[0] = 'D';
+ else if (inode->i_state & I_DIRTY_SYNC)
+ state[0] = 'd';
+
+ if (inode->i_state & I_LOCK)
+ state[0] = 'L';
+
+ refcnt = 0;
+ list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+ refcnt += atomic_read(&dentry->d_count);
+ }
+
+ seq_printf(m, "%10lu %10llu %8lu %7d ",
+ inode->i_ino,
+ DIV_ROUND_UP(size, 1024),
+ nrpages << (PAGE_CACHE_SHIFT - 10),
+ percent);
+
+ seq_printf(m, "%6d %5s %9lu ",
+ refcnt,
+ state,
+ (jiffies - inode->dirtied_when) / HZ);
+
+#ifdef CONFIG_PROC_FILECACHE_EXTRAS
+ seq_printf(m, "%8u %-16s",
+ inode->i_access_count,
+ inode->i_comm);
+#endif
+
+ seq_printf(m, "%02x:%02x(%s)\t",
+ MAJOR(inode->i_sb->s_dev),
+ MINOR(inode->i_sb->s_dev),
+ inode->i_sb->s_id);
+
+ if (list_empty(&inode->i_dentry)) {
+ if (!atomic_read(&inode->i_count))
+ seq_puts(m, "(noname)\n");
+ else
+ seq_printf(m, "(%02x:%02x)\n",
+ imajor(inode), iminor(inode));
+ } else {
+ struct path path = {
+ .mnt = NULL,
+ .dentry = list_entry(inode->i_dentry.next,
+ struct dentry, d_alias)
+ };
+
+ seq_path(m, &path, " \t\n\\");
+ seq_putc(m, '\n');
+ }
+}
+
+static int ii_show(struct seq_file *m, void *v)
+{
+ unsigned long index = *(loff_t *) v;
+ struct session *s = m->private;
+ struct inode *inode;
+
+ if (index == 0) {
+ seq_puts(m, "# filecache " FILECACHE_VERSION "\n");
+ seq_puts(m, "# ino size cached cached% "
+ "refcnt state age "
+#ifdef CONFIG_PROC_FILECACHE_EXTRAS
+ "accessed process "
+#endif
+ "dev\t\tfile\n");
+ }
+
+ inode = iwin_inode(s,index);
+ show_inode(m, inode);
+
+ return 0;
+}
+
+static void *ii_start(struct seq_file *m, loff_t *pos)
+{
+ struct session *s = m->private;
+
+ s->iwin.size = 0;
+ s->iwin.inodes = (struct inode **)
+ __get_free_pages( GFP_KERNEL, IWIN_PAGE_ORDER);
+ if (!s->iwin.inodes)
+ return NULL;
+
+ spin_lock(&inode_lock);
+
+ return iwin_inode(s, *pos) ? pos : NULL;
+}
+
+static void *ii_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct session *s = m->private;
+
+ (*pos)++;
+ return iwin_inode(s, *pos) ? pos : NULL;
+}
+
+static void ii_stop(struct seq_file *m, void *v)
+{
+ struct session *s = m->private;
+ struct inode *inode = s->ipos.inode;
+
+ if (!s->iwin.inodes)
+ return;
+
+ if (inode) {
+ __iget(inode);
+ s->ipos.state = inode->i_state;
+ }
+ spin_unlock(&inode_lock);
+
+ free_pages((unsigned long) s->iwin.inodes, IWIN_PAGE_ORDER);
+ if (s->ipos.pinned_inode)
+ iput(s->ipos.pinned_inode);
+ s->ipos.pinned_inode = inode;
+}
+
+/*
+ * Listing of cached page ranges of a file.
+ *
+ * Usage:
+ * echo 'file name' > /proc/filecache
+ * cat /proc/filecache
+ */
+
+unsigned long page_mask;
+#define PG_MMAP PG_lru /* reuse any non-relevant flag */
+#define PG_BUFFER PG_swapcache /* ditto */
+#define PG_DIRTY PG_error /* ditto */
+#define PG_WRITEBACK PG_buddy /* ditto */
+
+/*
+ * Page state names, prefixed by their abbreviations.
+ */
+struct {
+ unsigned long mask;
+ const char *name;
+ int faked;
+} page_flag [] = {
+ {1 << PG_referenced, "R:referenced", 0},
+ {1 << PG_active, "A:active", 0},
+ {1 << PG_MMAP, "M:mmap", 1},
+
+ {1 << PG_uptodate, "U:uptodate", 0},
+ {1 << PG_dirty, "D:dirty", 0},
+ {1 << PG_writeback, "W:writeback", 0},
+ {1 << PG_reclaim, "X:readahead", 0},
+
+ {1 << PG_private, "P:private", 0},
+ {1 << PG_owner_priv_1, "O:owner", 0},
+
+ {1 << PG_BUFFER, "b:buffer", 1},
+ {1 << PG_DIRTY, "d:dirty", 1},
+ {1 << PG_WRITEBACK, "w:writeback", 1},
+};
+
+static unsigned long page_flags(struct page* page)
+{
+ unsigned long flags;
+ struct address_space *mapping = page_mapping(page);
+
+ flags = page->flags & page_mask;
+
+ if (page_mapped(page))
+ flags |= (1 << PG_MMAP);
+
+ if (page_has_buffers(page))
+ flags |= (1 << PG_BUFFER);
+
+ if (mapping) {
+ if (radix_tree_tag_get(&mapping->page_tree,
+ page_index(page),
+ PAGECACHE_TAG_WRITEBACK))
+ flags |= (1 << PG_WRITEBACK);
+
+ if (radix_tree_tag_get(&mapping->page_tree,
+ page_index(page),
+ PAGECACHE_TAG_DIRTY))
+ flags |= (1 << PG_DIRTY);
+ }
+
+ return flags;
+}
+
+static int pages_similiar(struct page* page0, struct page* page)
+{
+ if (page_count(page0) != page_count(page))
+ return 0;
+
+ if (page_flags(page0) != page_flags(page))
+ return 0;
+
+ return 1;
+}
+
+static void show_range(struct seq_file *m, struct page* page, unsigned long len)
+{
+ int i;
+ unsigned long flags;
+
+ if (!m || !page)
+ return;
+
+ seq_printf(m, "%lu\t%lu\t", page->index, len);
+
+ flags = page_flags(page);
+ for (i = 0; i < ARRAY_SIZE(page_flag); i++)
+ seq_putc(m, (flags & page_flag[i].mask) ?
+ page_flag[i].name[0] : '_');
+
+ seq_printf(m, "\t%d\n", page_count(page));
+}
+
+#define BATCH_LINES 100
+static pgoff_t show_file_cache(struct seq_file *m,
+ struct address_space *mapping, pgoff_t start)
+{
+ int i;
+ int lines = 0;
+ pgoff_t len = 0;
+ struct pagevec pvec;
+ struct page *page;
+ struct page *page0 = NULL;
+
+ for (;;) {
+ pagevec_init(&pvec, 0);
+ pvec.nr = radix_tree_gang_lookup(&mapping->page_tree,
+ (void **)pvec.pages, start + len, PAGEVEC_SIZE);
+
+ if (pvec.nr == 0) {
+ show_range(m, page0, len);
+ start = ULONG_MAX;
+ goto out;
+ }
+
+ if (!page0)
+ page0 = pvec.pages[0];
+
+ for (i = 0; i < pvec.nr; i++) {
+ page = pvec.pages[i];
+
+ if (page->index == start + len &&
+ pages_similiar(page0, page))
+ len++;
+ else {
+ show_range(m, page0, len);
+ page0 = page;
+ start = page->index;
+ len = 1;
+ if (++lines > BATCH_LINES)
+ goto out;
+ }
+ }
+ }
+
+out:
+ return start;
+}
+
+static int pg_show(struct seq_file *m, void *v)
+{
+ struct session *s = m->private;
+ struct file *file = s->query_file;
+ pgoff_t offset;
+
+ if (!file)
+ return ii_show(m, v);
+
+ offset = *(loff_t *) v;
+
+ if (!offset) { /* print header */
+ int i;
+
+ seq_puts(m, "# file ");
+ seq_path(m, &file->f_path, " \t\n\\");
+
+ seq_puts(m, "\n# flags");
+ for (i = 0; i < ARRAY_SIZE(page_flag); i++)
+ seq_printf(m, " %s", page_flag[i].name);
+
+ seq_puts(m, "\n# idx\tlen\tstate\t\trefcnt\n");
+ }
+
+ s->start_offset = offset;
+ s->next_offset = show_file_cache(m, file->f_mapping, offset);
+
+ return 0;
+}
+
+static void *file_pos(struct file *file, loff_t *pos)
+{
+ loff_t size = i_size_read(file->f_mapping->host);
+ pgoff_t end = DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
+ pgoff_t offset = *pos;
+
+ return offset < end ? pos : NULL;
+}
+
+static void *pg_start(struct seq_file *m, loff_t *pos)
+{
+ struct session *s = m->private;
+ struct file *file = s->query_file;
+ pgoff_t offset = *pos;
+
+ if (!file)
+ return ii_start(m, pos);
+
+ rcu_read_lock();
+
+ if (offset - s->start_offset == 1)
+ *pos = s->next_offset;
+ return file_pos(file, pos);
+}
+
+static void *pg_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct session *s = m->private;
+ struct file *file = s->query_file;
+
+ if (!file)
+ return ii_next(m, v, pos);
+
+ *pos = s->next_offset;
+ return file_pos(file, pos);
+}
+
+static void pg_stop(struct seq_file *m, void *v)
+{
+ struct session *s = m->private;
+ struct file *file = s->query_file;
+
+ if (!file)
+ return ii_stop(m, v);
+
+ rcu_read_unlock();
+}
+
+struct seq_operations seq_filecache_op = {
+ .start = pg_start,
+ .next = pg_next,
+ .stop = pg_stop,
+ .show = pg_show,
+};
+
+/*
+ * Implement the manual drop-all-pagecache function
+ */
+
+#define MAX_INODES (PAGE_SIZE / sizeof(struct inode *))
+static int drop_pagecache(void)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct inode *inode;
+ struct inode **inodes;
+ unsigned long i, j, k;
+ int err = 0;
+
+ inodes = (struct inode **)__get_free_pages(GFP_KERNEL, IWIN_PAGE_ORDER);
+ if (!inodes)
+ return -ENOMEM;
+
+ for (i = 0; (head = get_inode_hash_budget(i)); i++) {
+ if (hlist_empty(head))
+ continue;
+
+ j = 0;
+ cond_resched();
+
+ /*
+ * Grab some inodes.
+ */
+ spin_lock(&inode_lock);
+ hlist_for_each (node, head) {
+ inode = hlist_entry(node, struct inode, i_hash);
+ if (!atomic_read(&inode->i_count))
+ continue;
+ if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
+ continue;
+ if (!inode->i_mapping || !inode->i_mapping->nrpages)
+ continue;
+ __iget(inode);
+ inodes[j++] = inode;
+ if (j >= MAX_INODES)
+ break;
+ }
+ spin_unlock(&inode_lock);
+
+ /*
+ * Free clean pages.
+ */
+ for (k = 0; k < j; k++) {
+ inode = inodes[k];
+ invalidate_mapping_pages(inode->i_mapping, 0, ~1);
+ iput(inode);
+ }
+
+ /*
+ * Simply ignore the remaining inodes.
+ */
+ if (j >= MAX_INODES && !err) {
+ printk(KERN_WARNING
+ "Too many collides in inode hash table.\n"
+ "Pls boot with a larger ihash_entries=XXX.\n");
+ err = -EAGAIN;
+ }
+ }
+
+ free_pages((unsigned long) inodes, IWIN_PAGE_ORDER);
+ return err;
+}
+
+static void drop_slabcache(void)
+{
+ int nr_objects;
+
+ do {
+ nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
+ } while (nr_objects > 10);
+}
+
+/*
+ * Proc file operations.
+ */
+
+static int filecache_open(struct inode *inode, struct file *proc_file)
+{
+ struct seq_file *m;
+ struct session *s;
+ unsigned size;
+ char *buf = 0;
+ int ret;
+
+ if (!try_module_get(THIS_MODULE))
+ return -ENOENT;
+
+ s = session_create();
+ if (IS_ERR(s)) {
+ ret = PTR_ERR(s);
+ goto out;
+ }
+ set_session(proc_file, s);
+
+ size = SBUF_SIZE;
+ buf = kmalloc(size, GFP_KERNEL);
+ if (!buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret = seq_open(proc_file, &seq_filecache_op);
+ if (!ret) {
+ m = proc_file->private_data;
+ m->private = s;
+ m->buf = buf;
+ m->size = size;
+ }
+
+out:
+ if (ret) {
+ kfree(s);
+ kfree(buf);
+ module_put(THIS_MODULE);
+ }
+ return ret;
+}
+
+static int filecache_release(struct inode *inode, struct file *proc_file)
+{
+ struct session *s = get_session(proc_file);
+ int ret;
+
+ session_release(s);
+ ret = seq_release(inode, proc_file);
+ module_put(THIS_MODULE);
+ return ret;
+}
+
+ssize_t filecache_write(struct file *proc_file, const char __user * buffer,
+ size_t count, loff_t *ppos)
+{
+ struct session *s;
+ char *name;
+ int err = 0;
+
+ if (count >= PATH_MAX + 5)
+ return -ENAMETOOLONG;
+
+ name = kmalloc(count+1, GFP_KERNEL);
+ if (!name)
+ return -ENOMEM;
+
+ if (copy_from_user(name, buffer, count)) {
+ err = -EFAULT;
+ goto out;
+ }
+
+ /* strip the optional newline */
+ if (count && name[count-1] == '\n')
+ name[count-1] = '\0';
+ else
+ name[count] = '\0';
+
+ s = get_session(proc_file);
+ if (!strcmp(name, "set private")) {
+ s->private_session = 1;
+ goto out;
+ }
+
+ if (!strncmp(name, "cat ", 4)) {
+ err = session_update_file(s, name+4);
+ goto out;
+ }
+
+ if (!strncmp(name, "ls", 2)) {
+ err = session_update_file(s, NULL);
+ if (!err)
+ err = ls_parse_options(name+2, s);
+ if (!err && !s->private_session) {
+ global_session.ls_dev = s->ls_dev;
+ global_session.ls_options = s->ls_options;
+ }
+ goto out;
+ }
+
+ if (!strncmp(name, "drop pagecache", 14)) {
+ err = drop_pagecache();
+ goto out;
+ }
+
+ if (!strncmp(name, "drop slabcache", 14)) {
+ drop_slabcache();
+ goto out;
+ }
+
+ /* err = -EINVAL; */
+ err = session_update_file(s, name);
+
+out:
+ kfree(name);
+
+ return err ? err : count;
+}
+
+static struct file_operations proc_filecache_fops = {
+ .owner = THIS_MODULE,
+ .open = filecache_open,
+ .release = filecache_release,
+ .write = filecache_write,
+ .read = seq_read,
+ .llseek = seq_lseek,
+};
+
+
+static __init int filecache_init(void)
+{
+ int i;
+ struct proc_dir_entry *entry;
+
+ entry = create_proc_entry("filecache", 0600, NULL);
+ if (entry)
+ entry->proc_fops = &proc_filecache_fops;
+
+ for (page_mask = i = 0; i < ARRAY_SIZE(page_flag); i++)
+ if (!page_flag[i].faked)
+ page_mask |= page_flag[i].mask;
+
+ return 0;
+}
+
+static void filecache_exit(void)
+{
+ remove_proc_entry("filecache", NULL);
+ if (global_session.query_file)
+ fput(global_session.query_file);
+}
+
+MODULE_AUTHOR("Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
+
+module_init(filecache_init);
+module_exit(filecache_exit);
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -775,6 +775,11 @@ struct inode {
void *i_security;
#endif
void *i_private; /* fs or device private pointer */
+
+#ifdef CONFIG_PROC_FILECACHE_EXTRAS
+ unsigned int i_access_count; /* opened how many times? */
+ char i_comm[16]; /* opened first by which app? */
+#endif
};

/*
@@ -860,6 +865,13 @@ static inline unsigned imajor(const stru
return MAJOR(inode->i_rdev);
}

+static inline void inode_accessed(struct inode *inode)
+{
+#ifdef CONFIG_PROC_FILECACHE_EXTRAS
+ inode->i_access_count++;
+#endif
+}
+
extern struct block_device *I_BDEV(struct inode *inode);

struct fown_struct {
@@ -2171,6 +2183,7 @@ extern void remove_inode_hash(struct ino
static inline void insert_inode_hash(struct inode *inode) {
__insert_inode_hash(inode, inode->i_ino);
}
+struct hlist_head * get_inode_hash_budget(unsigned long index);

extern struct file * get_empty_filp(void);
extern void file_move(struct file *f, struct list_head *list);
--- linux-2.6.orig/fs/open.c
+++ linux-2.6/fs/open.c
@@ -842,6 +842,7 @@ static struct file *__dentry_open(struct
goto cleanup_all;
}

+ inode_accessed(inode);
f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
--- linux-2.6.orig/fs/Kconfig
+++ linux-2.6/fs/Kconfig
@@ -265,4 +265,34 @@ endif
source "fs/nls/Kconfig"
source "fs/dlm/Kconfig"

+config PROC_FILECACHE
+ tristate "/proc/filecache support"
+ default m
+ depends on PROC_FS
+ help
+ This option creates a file /proc/filecache which enables one to
+ query/drop the cached files in memory.
+
+ A quick start guide:
+
+ # echo 'ls' > /proc/filecache
+ # head /proc/filecache
+
+ # echo 'cat /bin/bash' > /proc/filecache
+ # head /proc/filecache
+
+ # echo 'drop pagecache' > /proc/filecache
+ # echo 'drop slabcache' > /proc/filecache
+
+ For more details, please check Documentation/filesystems/proc.txt .
+
+ It can be a handy tool for sysadms and desktop users.
+
+config PROC_FILECACHE_EXTRAS
+ bool "track extra states"
+ default y
+ depends on PROC_FILECACHE
+ help
+ Track extra states that costs a little more time/space.
+
endmenu
--- linux-2.6.orig/fs/proc/Makefile
+++ linux-2.6/fs/proc/Makefile
@@ -2,7 +2,8 @@
# Makefile for the Linux proc filesystem routines.
#

-obj-$(CONFIG_PROC_FS) += proc.o
+obj-$(CONFIG_PROC_FS) += proc.o
+obj-$(CONFIG_PROC_FILECACHE) += filecache.o

proc-y := nommu.o task_nommu.o
proc-$(CONFIG_MMU) := mmu.o task_mmu.o