The patch titled
Subject: hugetlbfs: add O_TMPFILE support
has been added to the -mm tree. Its filename is
hugetlbfs-add-o_tmpfile-support.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/hugetlbfs-add-o_tmpfile-support.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/hugetlbfs-add-o_tmpfile-support.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Piotr Sarna <p.sarna@xxxxxxx>
Subject: hugetlbfs: add O_TMPFILE support
With hugetlbfs, a common pattern for mapping anonymous huge pages is to
create a temporary file first. Currently libraries like libhugetlbfs and
seastar create these with a standard mkstemp+unlink trick, but it would be
more robust to be able to simply pass the O_TMPFILE flag to open().
O_TMPFILE is already supported by several file systems like ext4 and xfs.
The implementation simply uses the existi= ng d_tmpfile utility function
to instantiate the dcache entry for the file.
Tested manually by successfully creating a temporary file by opening it
with (O_TMPFILE|O_RDWR) on mounted hugetlbfs and successfully mapping 2M
huge pages with it. Without the patch, trying to open a file with
O_TMPFILE results in -ENOSUP.
Link: http://lkml.kernel.org/r/bc9383eff6e1374d79f3a92257ae829ba1e6ae60.1573285189.git.p.sarna@xxxxxxx
Signed-off-by: Piotr Sarna <p.sarna@xxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/hugetlbfs/inode.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
--- a/fs/hugetlbfs/inode.c~hugetlbfs-add-o_tmpfile-support
+++ a/fs/hugetlbfs/inode.c
@@ -815,8 +815,11 @@ static struct inode *hugetlbfs_get_inode
/*
* File creation. Allocate an inode, and we're done..
*/
-static int hugetlbfs_mknod(struct inode *dir,
- struct dentry *dentry, umode_t mode, dev_t dev)
+static int do_hugetlbfs_mknod(struct inode *dir,
+ struct dentry *dentry,
+ umode_t mode,
+ dev_t dev,
+ bool tmpfile)
{
struct inode *inode;
int error = -ENOSPC;
@@ -824,13 +827,23 @@ static int hugetlbfs_mknod(struct inode
inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
if (inode) {
dir->i_ctime = dir->i_mtime = current_time(dir);
- d_instantiate(dentry, inode);
- dget(dentry); /* Extra count - pin the dentry in core */
+ if (tmpfile) {
+ d_tmpfile(dentry, inode);
+ } else {
+ d_instantiate(dentry, inode);
+ dget(dentry);/* Extra count - pin the dentry in core */
+ }
error = 0;
}
return error;
}
+static int hugetlbfs_mknod(struct inode *dir,
+ struct dentry *dentry, umode_t mode, dev_t dev)
+{
+ return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
+}
+
static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
@@ -844,6 +857,12 @@ static int hugetlbfs_create(struct inode
return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
}
+static int hugetlbfs_tmpfile(struct inode *dir,
+ struct dentry *dentry, umode_t mode)
+{
+ return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
+}
+
static int hugetlbfs_symlink(struct inode *dir,
struct dentry *dentry, const char *symname)
{
@@ -1102,6 +1121,7 @@ static const struct inode_operations hug
.mknod = hugetlbfs_mknod,
.rename = simple_rename,
.setattr = hugetlbfs_setattr,
+ .tmpfile = hugetlbfs_tmpfile,
};
static const struct inode_operations hugetlbfs_inode_operations = {
_
Patches currently in -mm which might be from p.sarna@xxxxxxx are
hugetlbfs-add-o_tmpfile-support.patch
