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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2024, Alibaba Cloud
*/
#include <linux/xxhash.h>
#include <linux/mount.h>
#include "internal.h"
#include "xattr.h"
#include "../internal.h"
static struct vfsmount *erofs_ishare_mnt;
static inline bool erofs_is_ishare_inode(struct inode *inode)
{
/* assumed FS_ONDEMAND is excluded with FS_PAGE_CACHE_SHARE feature */
return inode->i_sb->s_type == &erofs_anon_fs_type;
}
static int erofs_ishare_iget5_eq(struct inode *inode, void *data)
{
struct erofs_inode_fingerprint *fp1 = &EROFS_I(inode)->fingerprint;
struct erofs_inode_fingerprint *fp2 = data;
return fp1->size == fp2->size &&
!memcmp(fp1->opaque, fp2->opaque, fp2->size);
}
static int erofs_ishare_iget5_set(struct inode *inode, void *data)
{
struct erofs_inode *vi = EROFS_I(inode);
vi->fingerprint = *(struct erofs_inode_fingerprint *)data;
INIT_LIST_HEAD(&vi->ishare_list);
spin_lock_init(&vi->ishare_lock);
return 0;
}
bool erofs_ishare_fill_inode(struct inode *inode)
{
struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
struct erofs_inode *vi = EROFS_I(inode);
const struct address_space_operations *aops;
struct erofs_inode_fingerprint fp;
struct inode *sharedinode;
unsigned long hash;
aops = erofs_get_aops(inode, true);
if (IS_ERR(aops))
return false;
if (erofs_xattr_fill_inode_fingerprint(&fp, inode, sbi->domain_id))
return false;
hash = xxh32(fp.opaque, fp.size, 0);
sharedinode = iget5_locked(erofs_ishare_mnt->mnt_sb, hash,
erofs_ishare_iget5_eq, erofs_ishare_iget5_set,
&fp);
if (!sharedinode) {
kfree(fp.opaque);
return false;
}
if (inode_state_read_once(sharedinode) & I_NEW) {
sharedinode->i_mapping->a_ops = aops;
sharedinode->i_size = vi->vfs_inode.i_size;
unlock_new_inode(sharedinode);
} else {
kfree(fp.opaque);
if (aops != sharedinode->i_mapping->a_ops) {
iput(sharedinode);
return false;
}
if (sharedinode->i_size != vi->vfs_inode.i_size) {
_erofs_printk(inode->i_sb, KERN_WARNING
"size(%lld:%lld) not matches for the same fingerprint\n",
vi->vfs_inode.i_size, sharedinode->i_size);
iput(sharedinode);
return false;
}
}
vi->sharedinode = sharedinode;
INIT_LIST_HEAD(&vi->ishare_list);
spin_lock(&EROFS_I(sharedinode)->ishare_lock);
list_add(&vi->ishare_list, &EROFS_I(sharedinode)->ishare_list);
spin_unlock(&EROFS_I(sharedinode)->ishare_lock);
return true;
}
void erofs_ishare_free_inode(struct inode *inode)
{
struct erofs_inode *vi = EROFS_I(inode);
struct inode *sharedinode = vi->sharedinode;
if (!sharedinode)
return;
spin_lock(&EROFS_I(sharedinode)->ishare_lock);
list_del(&vi->ishare_list);
spin_unlock(&EROFS_I(sharedinode)->ishare_lock);
iput(sharedinode);
vi->sharedinode = NULL;
}
static int erofs_ishare_file_open(struct inode *inode, struct file *file)
{
struct inode *sharedinode = EROFS_I(inode)->sharedinode;
struct file *realfile;
if (file->f_flags & O_DIRECT)
return -EINVAL;
realfile = alloc_empty_backing_file(O_RDONLY|O_NOATIME, current_cred());
if (IS_ERR(realfile))
return PTR_ERR(realfile);
ihold(sharedinode);
realfile->f_op = &erofs_file_fops;
realfile->f_inode = sharedinode;
realfile->f_mapping = sharedinode->i_mapping;
path_get(&file->f_path);
backing_file_set_user_path(realfile, &file->f_path);
file_ra_state_init(&realfile->f_ra, file->f_mapping);
realfile->private_data = EROFS_I(inode);
file->private_data = realfile;
return 0;
}
static int erofs_ishare_file_release(struct inode *inode, struct file *file)
{
struct file *realfile = file->private_data;
iput(realfile->f_inode);
fput(realfile);
file->private_data = NULL;
return 0;
}
static ssize_t erofs_ishare_file_read_iter(struct kiocb *iocb,
struct iov_iter *to)
{
struct file *realfile = iocb->ki_filp->private_data;
struct kiocb dedup_iocb;
ssize_t nread;
if (!iov_iter_count(to))
return 0;
kiocb_clone(&dedup_iocb, iocb, realfile);
nread = filemap_read(&dedup_iocb, to, 0);
iocb->ki_pos = dedup_iocb.ki_pos;
return nread;
}
static int erofs_ishare_mmap(struct file *file, struct vm_area_struct *vma)
{
struct file *realfile = file->private_data;
vma_set_file(vma, realfile);
return generic_file_readonly_mmap(file, vma);
}
static int erofs_ishare_fadvise(struct file *file, loff_t offset,
loff_t len, int advice)
{
return vfs_fadvise(file->private_data, offset, len, advice);
}
const struct file_operations erofs_ishare_fops = {
.open = erofs_ishare_file_open,
.llseek = generic_file_llseek,
.read_iter = erofs_ishare_file_read_iter,
.mmap = erofs_ishare_mmap,
.release = erofs_ishare_file_release,
.get_unmapped_area = thp_get_unmapped_area,
.splice_read = filemap_splice_read,
.fadvise = erofs_ishare_fadvise,
};
struct inode *erofs_real_inode(struct inode *inode, bool *need_iput)
{
struct erofs_inode *vi, *vi_share;
struct inode *realinode;
*need_iput = false;
if (!erofs_is_ishare_inode(inode))
return inode;
vi_share = EROFS_I(inode);
spin_lock(&vi_share->ishare_lock);
/* fetch any one as real inode */
DBG_BUGON(list_empty(&vi_share->ishare_list));
list_for_each_entry(vi, &vi_share->ishare_list, ishare_list) {
realinode = igrab(&vi->vfs_inode);
if (realinode) {
*need_iput = true;
break;
}
}
spin_unlock(&vi_share->ishare_lock);
DBG_BUGON(!realinode);
return realinode;
}
int __init erofs_init_ishare(void)
{
erofs_ishare_mnt = kern_mount(&erofs_anon_fs_type);
return PTR_ERR_OR_ZERO(erofs_ishare_mnt);
}
void erofs_exit_ishare(void)
{
kern_unmount(erofs_ishare_mnt);
}
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