Per-mount allocated_ptys
Sukadev Bhattiprolu [Fri, 2 Jan 2009 13:41:21 +0000 (13:41 +0000)]
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.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/devpts/inode.c

index f96e10a..49d879d 100644 (file)
@@ -30,7 +30,6 @@
 #define PTMX_MINOR     2
 
 extern int pty_limit;                  /* Config limit on Unix98 ptys */
-static DEFINE_IDA(allocated_ptys);
 static DEFINE_MUTEX(allocated_ptys_lock);
 
 static struct vfsmount *devpts_mnt;
@@ -55,6 +54,15 @@ static const match_table_t tokens = {
        {Opt_err, NULL}
 };
 
+struct pts_fs_info {
+       struct ida 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)
@@ -126,6 +134,19 @@ static const struct super_operations devpts_sops = {
        .show_options   = devpts_show_options,
 };
 
+static void *new_pts_fs_info(void)
+{
+       struct pts_fs_info *fsi;
+
+       fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
+       if (!fsi)
+               return NULL;
+
+       ida_init(&fsi->allocated_ptys);
+
+       return fsi;
+}
+
 static int
 devpts_fill_super(struct super_block *s, void *data, int silent)
 {
@@ -137,9 +158,13 @@ devpts_fill_super(struct super_block *s, void *data, int silent)
        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;
@@ -155,6 +180,9 @@ devpts_fill_super(struct super_block *s, void *data, int silent)
        
        printk("devpts: get root dentry failed\n");
        iput(inode);
+
+free_fsi:
+       kfree(s->s_fs_info);
 fail:
        return -ENOMEM;
 }
@@ -165,11 +193,19 @@ static int devpts_get_sb(struct file_system_type *fs_type,
        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);
+
+       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,
 };
 
 /*
@@ -179,16 +215,18 @@ static struct file_system_type devpts_fs_type = {
 
 int devpts_new_index(struct inode *ptmx_inode)
 {
+       struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+       struct pts_fs_info *fsi = DEVPTS_SB(sb);
        int index;
        int ida_ret;
 
 retry:
-       if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
+       if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) {
                return -ENOMEM;
        }
 
        mutex_lock(&allocated_ptys_lock);
-       ida_ret = ida_get_new(&allocated_ptys, &index);
+       ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
        if (ida_ret < 0) {
                mutex_unlock(&allocated_ptys_lock);
                if (ida_ret == -EAGAIN)
@@ -197,7 +235,7 @@ retry:
        }
 
        if (index >= pty_limit) {
-               ida_remove(&allocated_ptys, index);
+               ida_remove(&fsi->allocated_ptys, index);
                mutex_unlock(&allocated_ptys_lock);
                return -EIO;
        }
@@ -207,8 +245,11 @@ retry:
 
 void devpts_kill_index(struct inode *ptmx_inode, int idx)
 {
+       struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+       struct pts_fs_info *fsi = DEVPTS_SB(sb);
+
        mutex_lock(&allocated_ptys_lock);
-       ida_remove(&allocated_ptys, idx);
+       ida_remove(&fsi->allocated_ptys, idx);
        mutex_unlock(&allocated_ptys_lock);
 }