1 files changed, 54 insertions, 11 deletions

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index db7fa5cab988..fa678abc9db1 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -37,7 +37,7 @@ static int proc_match(int len, const char *name, struct proc_dir_entry *de)
 #define PROC_BLOCK_SIZE (PAGE_SIZE - 1024)
 
 static ssize_t
-proc_file_read(struct file *file, char __user *buf, size_t nbytes,
+__proc_file_read(struct file *file, char __user *buf, size_t nbytes,
                loff_t *ppos)
 {
         struct inode * inode = file->f_path.dentry->d_inode;
@@ -183,19 +183,47 @@ proc_file_read(struct file *file, char __user *buf, size_t nbytes,
 }
 
 static ssize_t
+proc_file_read(struct file *file, char __user *buf, size_t nbytes,
+               loff_t *ppos)
+{
+        struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
+        ssize_t rv = -EIO;
+
+        spin_lock(&pde->pde_unload_lock);
+        if (!pde->proc_fops) {
+                spin_unlock(&pde->pde_unload_lock);
+                return rv;
+        }
+        pde->pde_users++;
+        spin_unlock(&pde->pde_unload_lock);
+
+        rv = __proc_file_read(file, buf, nbytes, ppos);
+
+        pde_users_dec(pde);
+        return rv;
+}
+
+static ssize_t
 proc_file_write(struct file *file, const char __user *buffer,
                 size_t count, loff_t *ppos)
 {
-        struct inode *inode = file->f_path.dentry->d_inode;
-        struct proc_dir_entry * dp;
-        
-        dp = PDE(inode);
-
-        if (!dp->write_proc)
-                return -EIO;
+        struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
+        ssize_t rv = -EIO;
+
+        if (pde->write_proc) {
+                spin_lock(&pde->pde_unload_lock);
+                if (!pde->proc_fops) {
+                        spin_unlock(&pde->pde_unload_lock);
+                        return rv;
+                }
+                pde->pde_users++;
+                spin_unlock(&pde->pde_unload_lock);
 
-        /* FIXME: does this routine need ppos?  probably... */
-        return dp->write_proc(file, buffer, count, dp->data);
+                /* FIXME: does this routine need ppos?  probably... */
+                rv = pde->write_proc(file, buffer, count, pde->data);
+                pde_users_dec(pde);
+        }
+        return rv;
 }
 
 
@@ -307,6 +335,21 @@ static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
 /*
  * Return an inode number between PROC_DYNAMIC_FIRST and
  * 0xffffffff, or zero on failure.
+ *
+ * Current inode allocations in the proc-fs (hex-numbers):
+ *
+ * 00000000             reserved
+ * 00000001-00000fff    static entries  (goners)
+ *      001             root-ino
+ *
+ * 00001000-00001fff    unused
+ * 0001xxxx-7fffxxxx    pid-dir entries for pid 1-7fff
+ * 80000000-efffffff    unused
+ * f0000000-ffffffff    dynamic entries
+ *
+ * Goal:
+ *      Once we split the thing into several virtual filesystems,
+ *      we will get rid of magical ranges (and this comment, BTW).
  */
 static unsigned int get_inode_number(void)
 {
@@ -363,7 +406,7 @@ static int proc_delete_dentry(struct dentry * dentry)
         return 1;
 }
 
-static struct dentry_operations proc_dentry_operations =
+static const struct dentry_operations proc_dentry_operations =
 {
         .d_delete       = proc_delete_dentry,
 };