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fs/xattr.c:listxattr(): fall back to vmalloc() if kmalloc() failed

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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>
This commit is contained in:
Andrew Morton 2012-04-05 14:25:07 -07:00 committed by Linus Torvalds
parent 703bf2d122
commit 0d08d7b7e1
1 changed files with 13 additions and 4 deletions
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17
fs/xattr.c
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@ -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;
}