From: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
Subject: [RFC][PATCH 4/8]: Per-mount allocated_ptys
To enable multiple mounts of devpts, 'allocated_ptys' must be a per-mount
variable rather than a global variable. Move 'allocated_ptys' into the
super_block's s_fs_info.
Changelog[v2]:
Define and use DEVPTS_SB() wrapper.
---
fs/devpts/inode.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 51 insertions(+), 7 deletions(-)
Index: linux-2.6.26-rc8-mm1/fs/devpts/inode.c
===================================================================
--- linux-2.6.26-rc8-mm1.orig/fs/devpts/inode.c 2008-08-20 13:16:47.000000000
-0700
+++ linux-2.6.26-rc8-mm1/fs/devpts/inode.c 2008-08-20 13:19:17.000000000
-0700
@@ -29,7 +29,6 @@
#define DEVPTS_DEFAULT_MODE 0600
extern int pty_limit; /* Config limit on Unix98 ptys */
-static DEFINE_IDR(allocated_ptys);
static DEFINE_MUTEX(allocated_ptys_lock);
static struct vfsmount *devpts_mnt;
@@ -54,6 +53,15 @@ static match_table_t tokens = {
{Opt_err, NULL}
};
+struct pts_fs_info {
+ struct idr allocated_ptys;
+};
+
+static inline struct pts_fs_info * DEVPTS_SB(struct super_block *sb)
+{
+ return sb->s_fs_info;
+}
+
static inline struct super_block *pts_sb_from_inode(struct inode *inode)
{
if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
@@ -125,6 +133,19 @@ static const struct super_operations dev
.show_options = devpts_show_options,
};
+static void *new_pts_fs_info(void)
+{
+ struct pts_fs_info *fsi;
+
+ fsi = kmalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
+ if (fsi) {
+ idr_init(&fsi->allocated_ptys);
+ }
+ printk(KERN_ERR "new_pts_fs_info(): Returning fsi %p\n", fsi);
+ return fsi;
+}
+
+
static int
devpts_fill_super(struct super_block *s, void *data, int silent)
{
@@ -136,9 +157,13 @@ devpts_fill_super(struct super_block *s,
s->s_op = &devpts_sops;
s->s_time_gran = 1;
+ s->s_fs_info = new_pts_fs_info();
+ if (!s->s_fs_info)
+ goto fail;
+
inode = new_inode(s);
if (!inode)
- goto fail;
+ goto free_fsi;
inode->i_ino = 1;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode->i_blocks = 0;
@@ -154,6 +179,9 @@ devpts_fill_super(struct super_block *s,
printk("devpts: get root dentry failed\n");
iput(inode);
+
+free_fsi:
+ kfree(s->s_fs_info);
fail:
return -ENOMEM;
}
@@ -164,11 +192,22 @@ static int devpts_get_sb(struct file_sys
return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
}
+
+static void devpts_kill_sb(struct super_block *sb)
+{
+ struct pts_fs_info *fsi = DEVPTS_SB(sb); // rcu ?
+
+ //idr_destroy(&fsi->allocated_ptys);
+ kfree(fsi);
+
+ kill_anon_super(sb);
+}
+
static struct file_system_type devpts_fs_type = {
.owner = THIS_MODULE,
.name = "devpts",
.get_sb = devpts_get_sb,
- .kill_sb = kill_anon_super,
+ .kill_sb = devpts_kill_sb,
};
/*
@@ -187,14 +226,16 @@ int devpts_new_index(struct inode *inode
{
int index;
int idr_ret;
+ struct super_block *sb = pts_sb_from_inode(inode);
+ struct pts_fs_info *fsi = DEVPTS_SB(sb); // need rcu ?
retry:
- if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
+ if (!idr_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) {
return -ENOMEM;
}
mutex_lock(&allocated_ptys_lock);
- idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
+ idr_ret = idr_get_new(&fsi->allocated_ptys, NULL, &index);
if (idr_ret < 0) {
mutex_unlock(&allocated_ptys_lock);
if (idr_ret == -EAGAIN)
@@ -203,7 +244,7 @@ retry:
}
if (index >= pty_limit) {
- idr_remove(&allocated_ptys, index);
+ idr_remove(&fsi->allocated_ptys, index);
mutex_unlock(&allocated_ptys_lock);
return -EIO;
}
@@ -213,8 +254,11 @@ retry:
void devpts_kill_index(struct inode *inode, int idx)
{
+ struct super_block *sb = pts_sb_from_inode(inode);
+ struct pts_fs_info *fsi = DEVPTS_SB(sb); // need rcu ?
+
mutex_lock(&allocated_ptys_lock);
- idr_remove(&allocated_ptys, idx);
+ idr_remove(&fsi->allocated_ptys, idx);
mutex_unlock(&allocated_ptys_lock);
}
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