vfs: use kmalloc() to allocate fdmem if possible

Use kmalloc() to allocate fdmem if possible.

vmalloc() is used as a fallback solution for fdmem allocation.  A new
helper function __free_fdtable() is introduced to reduce the lines of
code.

A potential bug, vfree() a memory allocated by kmalloc(), is fixed.

[akpm@linux-foundation.org: use __GFP_NOWARN, uninline alloc_fdmem() and free_fdmem()]
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/file.c b/fs/file.c
index cccaead962c2efe31c01029ca1ffa34676cffc8a..0be344755c020e8de53d26ff89f60d8a4778cf91 100644 (file)
--- a/fs/file.c
+++ b/fs/file.c
@@ -39,28 +39,27 @@ int sysctl_nr_open_max = 1024 * 1024; /* raised later */
  */
 static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
 
-static inline void * alloc_fdmem(unsigned int size)
+static inline void *alloc_fdmem(unsigned int size)
 {
-       if (size <= PAGE_SIZE)
-               return kmalloc(size, GFP_KERNEL);
-       else
-               return vmalloc(size);
+       void *data;
+
+       data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN);
+       if (data != NULL)
+               return data;
+
+       return vmalloc(size);
 }
 
-static inline void free_fdarr(struct fdtable *fdt)
+static void free_fdmem(void *ptr)
 {
-       if (fdt->max_fds <= (PAGE_SIZE / sizeof(struct file *)))
-               kfree(fdt->fd);
-       else
-               vfree(fdt->fd);
+       is_vmalloc_addr(ptr) ? vfree(ptr) : kfree(ptr);
 }
 
-static inline void free_fdset(struct fdtable *fdt)
+static void __free_fdtable(struct fdtable *fdt)
 {
-       if (fdt->max_fds <= (PAGE_SIZE * BITS_PER_BYTE / 2))
-               kfree(fdt->open_fds);
-       else
-               vfree(fdt->open_fds);
+       free_fdmem(fdt->fd);
+       free_fdmem(fdt->open_fds);
+       kfree(fdt);
 }
 
 static void free_fdtable_work(struct work_struct *work)
@@ -75,9 +74,8 @@ static void free_fdtable_work(struct work_struct *work)
        spin_unlock_bh(&f->lock);
        while(fdt) {
                struct fdtable *next = fdt->next;
-               vfree(fdt->fd);
-               free_fdset(fdt);
-               kfree(fdt);
+
+               __free_fdtable(fdt);
                fdt = next;
        }
 }
@@ -98,7 +96,7 @@ void free_fdtable_rcu(struct rcu_head *rcu)
                                container_of(fdt, struct files_struct, fdtab));
                return;
        }
-       if (fdt->max_fds <= (PAGE_SIZE / sizeof(struct file *))) {
+       if (!is_vmalloc_addr(fdt->fd) && !is_vmalloc_addr(fdt->open_fds)) {
                kfree(fdt->fd);
                kfree(fdt->open_fds);
                kfree(fdt);
@@ -183,7 +181,7 @@ static struct fdtable * alloc_fdtable(unsigned int nr)
        return fdt;
 
 out_arr:
-       free_fdarr(fdt);
+       free_fdmem(fdt->fd);
 out_fdt:
        kfree(fdt);
 out:
@@ -213,9 +211,7 @@ static int expand_fdtable(struct files_struct *files, int nr)
         * caller and alloc_fdtable().  Cheaper to catch it here...
         */
        if (unlikely(new_fdt->max_fds <= nr)) {
-               free_fdarr(new_fdt);
-               free_fdset(new_fdt);
-               kfree(new_fdt);
+               __free_fdtable(new_fdt);
                return -EMFILE;
        }
        /*
@@ -231,9 +227,7 @@ static int expand_fdtable(struct files_struct *files, int nr)
                        free_fdtable(cur_fdt);
        } else {
                /* Somebody else expanded, so undo our attempt */
-               free_fdarr(new_fdt);
-               free_fdset(new_fdt);
-               kfree(new_fdt);
+               __free_fdtable(new_fdt);
        }
        return 1;
 }
@@ -323,11 +317,8 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
        while (unlikely(open_files > new_fdt->max_fds)) {
                spin_unlock(&oldf->file_lock);
 
-               if (new_fdt != &newf->fdtab) {
-                       free_fdarr(new_fdt);
-                       free_fdset(new_fdt);
-                       kfree(new_fdt);
-               }
+               if (new_fdt != &newf->fdtab)
+                       __free_fdtable(new_fdt);
 
                new_fdt = alloc_fdtable(open_files - 1);
                if (!new_fdt) {
@@ -337,9 +328,7 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
 
                /* beyond sysctl_nr_open; nothing to do */
                if (unlikely(new_fdt->max_fds < open_files)) {
-                       free_fdarr(new_fdt);
-                       free_fdset(new_fdt);
-                       kfree(new_fdt);
+                       __free_fdtable(new_fdt);
                        *errorp = -EMFILE;
                        goto out_release;
                }