fs/xattr.c:listxattr(): fall back to vmalloc() if kmalloc() failed
authorAndrew Morton <akpm@linux-foundation.org>
Thu, 5 Apr 2012 21:25:07 +0000 (14:25 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 5 Apr 2012 22:25:50 +0000 (15:25 -0700)
This allocation can be as large as 64k.  As David points out, "falling
back to vmalloc here is much better solution than failing to retreive
the attribute - it will work no matter how fragmented memory gets.  That
means we don't get incomplete backups occurring after days or months of
uptime and successful backups".

Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: David Rientjes <rientjes@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/xattr.c

index a14d842ccb217f86e675bc761d512e13219cba28..d14afbae3c135973c66b9c88d4c5315836b86137 100644 (file)
@@ -19,8 +19,9 @@
 #include <linux/export.h>
 #include <linux/fsnotify.h>
 #include <linux/audit.h>
-#include <asm/uaccess.h>
+#include <linux/vmalloc.h>
 
+#include <asm/uaccess.h>
 
 /*
  * Check permissions for extended attribute access.  This is a bit complicated
@@ -492,13 +493,18 @@ listxattr(struct dentry *d, char __user *list, size_t size)
 {
        ssize_t error;
        char *klist = NULL;
+       char *vlist = NULL;     /* If non-NULL, we used vmalloc() */
 
        if (size) {
                if (size > XATTR_LIST_MAX)
                        size = XATTR_LIST_MAX;
                klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);
-               if (!klist)
-                       return -ENOMEM;
+               if (!klist) {
+                       vlist = vmalloc(size);
+                       if (!vlist)
+                               return -ENOMEM;
+                       klist = vlist;
+               }
        }
 
        error = vfs_listxattr(d, klist, size);
@@ -510,7 +516,10 @@ listxattr(struct dentry *d, char __user *list, size_t size)
                   than XATTR_LIST_MAX bytes. Not possible. */
                error = -E2BIG;
        }
-       kfree(klist);
+       if (vlist)
+               vfree(vlist);
+       else
+               kfree(klist);
        return error;
 }