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>

1 files changed, 23 insertions, 34 deletions

diff --git a/fs/file.c b/fs/file.c
index cccaead962c2..0be344755c02 100644
--- 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;
                 }