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hugetlbfs: add O_TMPFILE support

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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@tlen.pl
Signed-off-by: Piotr Sarna <p.sarna@tlen.pl>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Piotr Sarna 2019-11-30 17:56:43 -08:00 committed by Linus Torvalds
parent 1f9dccb25b
commit 1ab5b82f54
1 changed files with 24 additions and 4 deletions
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28
fs/hugetlbfs/inode.c
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@ -815,8 +815,11 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb,
/*
* 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 *dir,
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 *dir, struct dentry *dentry, umode_t mo
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 hugetlbfs_dir_inode_operations = {
.mknod = hugetlbfs_mknod,
.rename = simple_rename,
.setattr = hugetlbfs_setattr,
.tmpfile = hugetlbfs_tmpfile,
};
static const struct inode_operations hugetlbfs_inode_operations = {