The patch titled
Subject: userfaultfd: convert to use anon_inode_getfd()
has been added to the -mm tree. Its filename is
userfaultfd-convert-to-use-anon_inode_getfd.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-convert-to-use-anon_inode_getfd.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-convert-to-use-anon_inode_getfd.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Eric Biggers <ebiggers@xxxxxxxxxx>
Subject: userfaultfd: convert to use anon_inode_getfd()
Nothing actually calls userfaultfd_file_create() besides the userfaultfd()
system call itself. So simplify things by folding it into the system call
and using anon_inode_getfd() instead of anon_inode_getfile(). Do the same
in resolve_userfault_fork() as well. This removes over 50 lines with no
change in functionality.
Link: http://lkml.kernel.org/r/20171229212403.22800-1-ebiggers3@xxxxxxxxx
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 70 +++++----------------------------------------
1 file changed, 9 insertions(+), 61 deletions(-)
diff -puN fs/userfaultfd.c~userfaultfd-convert-to-use-anon_inode_getfd fs/userfaultfd.c
--- a/fs/userfaultfd.c~userfaultfd-convert-to-use-anon_inode_getfd
+++ a/fs/userfaultfd.c
@@ -988,24 +988,14 @@ static int resolve_userfault_fork(struct
struct uffd_msg *msg)
{
int fd;
- struct file *file;
- unsigned int flags = new->flags & UFFD_SHARED_FCNTL_FLAGS;
- fd = get_unused_fd_flags(flags);
+ fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new,
+ O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS));
if (fd < 0)
return fd;
- file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, new,
- O_RDWR | flags);
- if (IS_ERR(file)) {
- put_unused_fd(fd);
- return PTR_ERR(file);
- }
-
- fd_install(fd, file);
msg->arg.reserved.reserved1 = 0;
msg->arg.fork.ufd = fd;
-
return 0;
}
@@ -1887,24 +1877,10 @@ static void init_once_userfaultfd_ctx(vo
seqcount_init(&ctx->refile_seq);
}
-/**
- * userfaultfd_file_create - Creates a userfaultfd file pointer.
- * @flags: Flags for the userfaultfd file.
- *
- * This function creates a userfaultfd file pointer, w/out installing
- * it into the fd table. This is useful when the userfaultfd file is
- * used during the initialization of data structures that require
- * extra setup after the userfaultfd creation. So the userfaultfd
- * creation is split into the file pointer creation phase, and the
- * file descriptor installation phase. In this way races with
- * userspace closing the newly installed file descriptor can be
- * avoided. Returns a userfaultfd file pointer, or a proper error
- * pointer.
- */
-static struct file *userfaultfd_file_create(int flags)
+SYSCALL_DEFINE1(userfaultfd, int, flags)
{
- struct file *file;
struct userfaultfd_ctx *ctx;
+ int fd;
BUG_ON(!current->mm);
@@ -1912,14 +1888,12 @@ static struct file *userfaultfd_file_cre
BUILD_BUG_ON(UFFD_CLOEXEC != O_CLOEXEC);
BUILD_BUG_ON(UFFD_NONBLOCK != O_NONBLOCK);
- file = ERR_PTR(-EINVAL);
if (flags & ~UFFD_SHARED_FCNTL_FLAGS)
- goto out;
+ return -EINVAL;
- file = ERR_PTR(-ENOMEM);
ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL);
if (!ctx)
- goto out;
+ return -ENOMEM;
atomic_set(&ctx->refcount, 1);
ctx->flags = flags;
@@ -1930,39 +1904,13 @@ static struct file *userfaultfd_file_cre
/* prevent the mm struct to be freed */
mmgrab(ctx->mm);
- file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, ctx,
- O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
- if (IS_ERR(file)) {
+ fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx,
+ O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
+ if (fd < 0) {
mmdrop(ctx->mm);
kmem_cache_free(userfaultfd_ctx_cachep, ctx);
}
-out:
- return file;
-}
-
-SYSCALL_DEFINE1(userfaultfd, int, flags)
-{
- int fd, error;
- struct file *file;
-
- error = get_unused_fd_flags(flags & UFFD_SHARED_FCNTL_FLAGS);
- if (error < 0)
- return error;
- fd = error;
-
- file = userfaultfd_file_create(flags);
- if (IS_ERR(file)) {
- error = PTR_ERR(file);
- goto err_put_unused_fd;
- }
- fd_install(fd, file);
-
return fd;
-
-err_put_unused_fd:
- put_unused_fd(fd);
-
- return error;
}
static int __init userfaultfd_init(void)
_
Patches currently in -mm which might be from ebiggers@xxxxxxxxxx are
userfaultfd-convert-to-use-anon_inode_getfd.patch
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