hugetlbfs: Do not call user_shm_lock() for MAP_HUGETLB fix

[Eric B Munson <ebmunson@us.ibm.com>]

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The patch
hugetlbfs-allow-the-creation-of-files-suitable-for-map_private-on-the-vfs-internal-mount.patch
alters can_do_hugetlb_shm() to check if a file is being created for shared
memory or mmap(). If this returns false, we then unconditionally call
user_shm_lock() triggering a warning. This block should never be entered
for MAP_HUGETLB. This patch partially reverts the problem and fixes the check.

This patch should be considered a fix to
hugetlbfs-allow-the-creation-of-files-suitable-for-map_private-on-the-vfs-internal-mount.patch.

From: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>
---
 fs/hugetlbfs/inode.c |   12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 49d2bf9..c944cc1 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -910,15 +910,9 @@ static struct file_system_type hugetlbfs_fs_type = {

 static struct vfsmount *hugetlbfs_vfsmount;

-static int can_do_hugetlb_shm(int creat_flags)
+static int can_do_hugetlb_shm(void)
 {
-       if (creat_flags != HUGETLB_SHMFS_INODE)
-               return 0;
-       if (capable(CAP_IPC_LOCK))
-               return 1;
-       if (in_group_p(sysctl_hugetlb_shm_group))
-               return 1;
-       return 0;
+       return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group);
 }

 struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag,
@@ -934,7 +928,7 @@ struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag,
        if (!hugetlbfs_vfsmount)
                return ERR_PTR(-ENOENT);

-       if (!can_do_hugetlb_shm(creat_flags)) {
+       if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
                *user = current_user();
                if (user_shm_lock(size, *user)) {
                        WARN_ONCE(1,


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