// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2022, Alibaba Cloud
* Copyright (C) 2022, Bytedance Inc. All rights reserved.
*/
#include <linux/pseudo_fs.h>
#include <linux/fscache.h>
#include "internal.h"
static DEFINE_MUTEX(erofs_domain_list_lock);
static DEFINE_MUTEX(erofs_domain_cookies_lock);
static LIST_HEAD(erofs_domain_list);
static LIST_HEAD(erofs_domain_cookies_list);
static struct vfsmount *erofs_pseudo_mnt;
static int erofs_anon_init_fs_context(struct fs_context *fc)
{
return init_pseudo(fc, EROFS_SUPER_MAGIC) ? 0 : -ENOMEM;
}
static struct file_system_type erofs_anon_fs_type = {
.owner = THIS_MODULE,
.name = "pseudo_erofs",
.init_fs_context = erofs_anon_init_fs_context,
.kill_sb = kill_anon_super,
};
struct erofs_fscache_io {
struct netfs_cache_resources cres;
struct iov_iter iter;
netfs_io_terminated_t end_io;
void *private;
refcount_t ref;
};
struct erofs_fscache_rq {
struct address_space *mapping; /* The mapping being accessed */
loff_t start; /* Start position */
size_t len; /* Length of the request */
size_t submitted; /* Length of submitted */
short error; /* 0 or error that occurred */
refcount_t ref;
};
static bool erofs_fscache_io_put(struct erofs_fscache_io *io)
{
if (!refcount_dec_and_test(&io->ref))
return false;
if (io->cres.ops)
io->cres.ops->end_operation(&io->cres);
kfree(io);
return true;
}
static void erofs_fscache_req_complete(struct erofs_fscache_rq *req)
{
struct folio *folio;
bool failed = req->error;
pgoff_t start_page = req->start / PAGE_SIZE;
pgoff_t last_page = ((req->start + req->len) / PAGE_SIZE) - 1;
XA_STATE(xas, &req->mapping->i_pages, start_page);
rcu_read_lock();
xas_for_each(&xas, folio, last_page) {
if (xas_retry(&xas, folio))
continue;
if (!failed)
folio_mark_uptodate(folio);
folio_unlock(folio);
}
rcu_read_unlock();
}
static void erofs_fscache_req_put(struct erofs_fscache_rq *req)
{
if (!refcount_dec_and_test(&req->ref))
return;
erofs_fscache_req_complete(req);
kfree(req);
}
static struct erofs_fscache_rq *erofs_fscache_req_alloc(struct address_space *mapping,
loff_t start, size_t len)
{
struct erofs_fscache_rq *req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
return NULL;
req->mapping = mapping;
req->start = start;
req->len = len;
refcount_set(&req->ref, 1);
return req;
}
static void erofs_fscache_req_io_put(struct erofs_fscache_io *io)
{
struct erofs_fscache_rq *req = io->private;
if (erofs_fscache_io_put(io))
erofs_fscache_req_put(req);
}
static void erofs_fscache_req_end_io(void *priv,
ssize_t transferred_or_error, bool was_async)
{
struct erofs_fscache_io *io = priv;
struct erofs_fscache_rq *req = io->private;
if (IS_ERR_VALUE(transferred_or_error))
req->error = transferred_or_error;
erofs_fscache_req_io_put(io);
}
static struct erofs_fscache_io *erofs_fscache_req_io_alloc(struct erofs_fscache_rq *req)
{
struct erofs_fscache_io *io = kzalloc(sizeof(*io), GFP_KERNEL);
if (!io)
return NULL;
io->end_io = erofs_fscache_req_end_io;
io->private = req;
refcount_inc(&req->ref);
refcount_set(&io->ref, 1);
return io;
}
/*
* Read data from fscache described by cookie at pstart physical address
* offset, and fill the read data into buffer described by io->iter.
*/
static int erofs_fscache_read_io_async(struct fscache_cookie *cookie,
loff_t pstart, struct erofs_fscache_io *io)
{
enum netfs_io_source source;
struct netfs_cache_resources *cres = &io->cres;
struct iov_iter *iter = &io->iter;
int ret;
ret = fscache_begin_read_operation(cres, cookie);
if (ret)
return ret;
while (iov_iter_count(iter)) {
size_t orig_count = iov_iter_count(iter), len = orig_count;
unsigned long flags = 1 << NETFS_SREQ_ONDEMAND;
source = cres->ops->prepare_ondemand_read(cres,
pstart, &len, LLONG_MAX, &flags, 0);
if (WARN_ON(len == 0))
source = NETFS_INVALID_READ;
if (source != NETFS_READ_FROM_CACHE) {
erofs_err(NULL, "prepare_ondemand_read failed (source %d)", source);
return -EIO;
}
iov_iter_truncate(iter, len);
refcount_inc(&io->ref);
ret = fscache_read(cres, pstart, iter, NETFS_READ_HOLE_FAIL,
io->end_io, io);
if (ret == -EIOCBQUEUED)
ret = 0;
if (ret) {
erofs_err(NULL, "fscache_read failed (ret %d)", ret);
return ret;
}
if (WARN_ON(iov_iter_count(iter)))
return -EIO;
iov_iter_reexpand(iter, orig_count - len);
pstart += len;
}
return 0;
}
struct erofs_fscache_bio {
struct erofs_fscache_io io;
struct bio bio; /* w/o bdev to share bio_add_page/endio() */
struct bio_vec bvecs[BIO_MAX_VECS];
};
static void erofs_fscache_bio_endio(void *priv,
ssize_t transferred_or_error, bool was_async)
{
struct erofs_fscache_bio *io = priv;
if (IS_ERR_VALUE(transferred_or_error))
io->bio.bi_status = errno_to_blk_status(transferred_or_error);
io->bio.bi_end_io(&io->bio);
BUILD_BUG_ON(offsetof(struct erofs_fscache_bio, io) != 0);
erofs_fscache_io_put(&io->io);
}
struct bio *erofs_fscache_bio_alloc(struct erofs_map_dev *mdev)
{
struct erofs_fscache_bio *io;
io = kmalloc(sizeof(*io), GFP_KERNEL | __GFP_NOFAIL);
bio_init(&io->bio, NULL, io->bvecs, BIO_MAX_VECS, REQ_OP_READ);
io->io.private = mdev->m_fscache->cookie;
io->io.end_io = erofs_fscache_bio_endio;
refcount_set(&io->io.ref, 1);
return &io->bio;
}
void erofs_fscache_submit_bio(struct bio *bio)
{
struct erofs_fscache_bio *io = container_of(bio,
struct erofs_fscache_bio, bio);
int ret;
iov_iter_bvec(&io->io.iter, ITER_DEST, io->bvecs, bio->bi_vcnt,
bio->bi_iter.bi_size);
ret = erofs_fscache_read_io_async(io->io.private,
bio->bi_iter.bi_sector << 9, &io->io);
erofs_fscache_io_put(&io->io);
if (!ret)
return;
bio->bi_status = errno_to_blk_status(ret);
bio->bi_end_io(bio);
}
static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
{
struct erofs_fscache *ctx = folio->mapping->host->i_private;
int ret = -ENOMEM;
struct erofs_fscache_rq *req;
struct erofs_fscache_io *io;
req = erofs_fscache_req_alloc(folio->mapping,
folio_pos(folio), folio_size(folio));
if (!req) {
folio_unlock(folio);
return ret;
}
io = erofs_fscache_req_io_alloc(req);
if (!io) {
req->error = ret;
goto out;
}
iov_iter_xarray(&io->iter, ITER_DEST, &folio->mapping->i_pages,
folio_pos(folio), folio_size(folio));
ret = erofs_fscache_read_io_async(ctx->cookie, folio_pos(folio), io);
if (ret)
req->error = ret;
erofs_fscache_req_io_put(io);
out:
erofs_fscache_req_put(req);
return ret;
}
static int erofs_fscache_data_read_slice(struct erofs_fscache_rq *req)
{
struct address_space *mapping = req->mapping;
struct inode *inode = mapping->host;
struct super_block *sb = inode->i_sb;
struct erofs_fscache_io *io;
struct erofs_map_blocks map;
struct erofs_map_dev mdev;
loff_t pos = req->start + req->submitted;
size_t count;
int ret;
map.m_la = pos;
ret = erofs_map_blocks(inode, &map);
if (ret)
return ret;
if (map.m_flags & EROFS_MAP_META) {
struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
struct iov_iter iter;
size_t size = map.m_llen;
void *src;
src = erofs_read_metabuf(&buf, sb, map.m_pa, EROFS_KMAP);
if (IS_ERR(src))
return PTR_ERR(src);
iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, PAGE_SIZE);
if (copy_to_iter(src, size, &iter) != size) {
erofs_put_metabuf(&buf);
return -EFAULT;
}
iov_iter_zero(PAGE_SIZE - size, &iter);
erofs_put_metabuf(&buf);
req->submitted += PAGE_SIZE;
return 0;
}
count = req->len - req->submitted;
if (!(map.m_flags & EROFS_MAP_MAPPED)) {
struct iov_iter iter;
iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, count);
iov_iter_zero(count, &iter);
req->submitted += count;
return 0;
}
count = min_t(size_t, map.m_llen - (pos - map.m_la), count);
DBG_BUGON(!count || count % PAGE_SIZE);
mdev = (struct erofs_map_dev) {
.m_deviceid = map.m_deviceid,
.m_pa = map.m_pa,
};
ret = erofs_map_dev(sb, &mdev);
if (ret)
return ret;
io = erofs_fscache_req_io_alloc(req);
if (!io)
return -ENOMEM;
iov_iter_xarray(&io->iter, ITER_DEST, &mapping->i_pages, pos, count);
ret = erofs_fscache_read_io_async(mdev.m_fscache->cookie,
mdev.m_pa + (pos - map.m_la), io);
erofs_fscache_req_io_put(io);
req->submitted += count;
return ret;
}
static int erofs_fscache_data_read(struct erofs_fscache_rq *req)
{
int ret;
do {
ret = erofs_fscache_data_read_slice(req);
if (ret)
req->error = ret;
} while (!ret && req->submitted < req->len);
return ret;
}
static int erofs_fscache_read_folio(struct file *file, struct folio *folio)
{
struct erofs_fscache_rq *req;
int ret;
req = erofs_fscache_req_alloc(folio->mapping,
folio_pos(folio), folio_size(folio));
if (!req) {
folio_unlock(folio);
return -ENOMEM;
}
ret = erofs_fscache_data_read(req);
erofs_fscache_req_put(req);
return ret;
}
static void erofs_fscache_readahead(struct readahead_control *rac)
{
struct erofs_fscache_rq *req;
if (!readahead_count(rac))
return;
req = erofs_fscache_req_alloc(rac->mapping,
readahead_pos(rac), readahead_length(rac));
if (!req)
return;
/* The request completion will drop refs on the folios. */
while (readahead_folio(rac))
;
erofs_fscache_data_read(req);
erofs_fscache_req_put(req);
}
static const struct address_space_operations erofs_fscache_meta_aops = {
.read_folio = erofs_fscache_meta_read_folio,
};
const struct address_space_operations erofs_fscache_access_aops = {
.read_folio = erofs_fscache_read_folio,
.readahead = erofs_fscache_readahead,
};
static void erofs_fscache_domain_put(struct erofs_domain *domain)
{
mutex_lock(&erofs_domain_list_lock);
if (refcount_dec_and_test(&domain->ref)) {
list_del(&domain->list);
if (list_empty(&erofs_domain_list)) {
kern_unmount(erofs_pseudo_mnt);
erofs_pseudo_mnt = NULL;
}
fscache_relinquish_volume(domain->volume, NULL, false);
mutex_unlock(&erofs_domain_list_lock);
kfree(domain->domain_id);
kfree(domain);
return;
}
mutex_unlock(&erofs_domain_list_lock);
}
static int erofs_fscache_register_volume(struct super_block *sb)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
char *domain_id = sbi->domain_id;
struct fscache_volume *volume;
char *name;
int ret = 0;
name = kasprintf(GFP_KERNEL, "erofs,%s",
domain_id ? domain_id : sbi->fsid);
if (!name)
return -ENOMEM;
volume = fscache_acquire_volume(name, NULL, NULL, 0);
if (IS_ERR_OR_NULL(volume)) {
erofs_err(sb, "failed to register volume for %s", name);
ret = volume ? PTR_ERR(volume) : -EOPNOTSUPP;
volume = NULL;
}
sbi->volume = volume;
kfree(name);
return ret;
}
static int erofs_fscache_init_domain(struct super_block *sb)
{
int err;
struct erofs_domain *domain;
struct erofs_sb_info *sbi = EROFS_SB(sb);
domain = kzalloc(sizeof(struct erofs_domain), GFP_KERNEL);
if (!domain)
return -ENOMEM;
domain->domain_id = kstrdup(sbi->domain_id, GFP_KERNEL);
if (!domain->domain_id) {
kfree(domain);
return -ENOMEM;
}
err = erofs_fscache_register_volume(sb);
if (err)
goto out;
if (!erofs_pseudo_mnt) {
struct vfsmount *mnt = kern_mount(&erofs_anon_fs_type);
if (IS_ERR(mnt)) {
err = PTR_ERR(mnt);
goto out;
}
erofs_pseudo_mnt = mnt;
}
domain->volume = sbi->volume;
refcount_set(&domain->ref, 1);
list_add(&domain->list, &erofs_domain_list);
sbi->domain = domain;
return 0;
out:
kfree(domain->domain_id);
kfree(domain);
return err;
}
static int erofs_fscache_register_domain(struct super_block *sb)
{
int err;
struct erofs_domain *domain;
struct erofs_sb_info *sbi = EROFS_SB(sb);
mutex_lock(&erofs_domain_list_lock);
list_for_each_entry(domain, &erofs_domain_list, list) {
if (!strcmp(domain->domain_id, sbi->domain_id)) {
sbi->domain = domain;
sbi->volume = domain->volume;
refcount_inc(&domain->ref);
mutex_unlock(&erofs_domain_list_lock);
return 0;
}
}
err = erofs_fscache_init_domain(sb);
mutex_unlock(&erofs_domain_list_lock);
return err;
}
static struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
char *name, unsigned int flags)
{
struct fscache_volume *volume = EROFS_SB(sb)->volume;
struct erofs_fscache *ctx;
struct fscache_cookie *cookie;
struct super_block *isb;
struct inode *inode;
int ret;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return ERR_PTR(-ENOMEM);
INIT_LIST_HEAD(&ctx->node);
refcount_set(&ctx->ref, 1);
cookie = fscache_acquire_cookie(volume, FSCACHE_ADV_WANT_CACHE_SIZE,
name, strlen(name), NULL, 0, 0);
if (!cookie) {
erofs_err(sb, "failed to get cookie for %s", name);
ret = -EINVAL;
goto err;
}
fscache_use_cookie(cookie, false);
/*
* Allocate anonymous inode in global pseudo mount for shareable blobs,
* so that they are accessible among erofs fs instances.
*/
isb = flags & EROFS_REG_COOKIE_SHARE ? erofs_pseudo_mnt->mnt_sb : sb;
inode = new_inode(isb);
if (!inode) {
erofs_err(sb, "failed to get anon inode for %s", name);
ret = -ENOMEM;
goto err_cookie;
}
inode->i_size = OFFSET_MAX;
inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
mapping_set_gfp_mask(inode->i_mapping, GFP_KERNEL);
inode->i_blkbits = EROFS_SB(sb)->blkszbits;
inode->i_private = ctx;
ctx->cookie = cookie;
ctx->inode = inode;
return ctx;
err_cookie:
fscache_unuse_cookie(cookie, NULL, NULL);
fscache_relinquish_cookie(cookie, false);
err:
kfree(ctx);
return ERR_PTR(ret);
}
static void erofs_fscache_relinquish_cookie(struct erofs_fscache *ctx)
{
fscache_unuse_cookie(ctx->cookie, NULL, NULL);
fscache_relinquish_cookie(ctx->cookie, false);
iput(ctx->inode);
kfree(ctx->name);
kfree(ctx);
}
static struct erofs_fscache *erofs_domain_init_cookie(struct super_block *sb,
char *name, unsigned int flags)
{
struct erofs_fscache *ctx;
struct erofs_domain *domain = EROFS_SB(sb)->domain;
ctx = erofs_fscache_acquire_cookie(sb, name, flags);
if (IS_ERR(ctx))
return ctx;
ctx->name = kstrdup(name, GFP_KERNEL);
if (!ctx->name) {
erofs_fscache_relinquish_cookie(ctx);
return ERR_PTR(-ENOMEM);
}
refcount_inc(&domain->ref);
ctx->domain = domain;
list_add(&ctx->node, &erofs_domain_cookies_list);
return ctx;
}
static struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
char *name, unsigned int flags)
{
struct erofs_fscache *ctx;
struct erofs_domain *domain = EROFS_SB(sb)->domain;
flags |= EROFS_REG_COOKIE_SHARE;
mutex_lock(&erofs_domain_cookies_lock);
list_for_each_entry(ctx, &erofs_domain_cookies_list, node) {
if (ctx->domain != domain || strcmp(ctx->name, name))
continue;
if (!(flags & EROFS_REG_COOKIE_NEED_NOEXIST)) {
refcount_inc(&ctx->ref);
} else {
erofs_err(sb, "%s already exists in domain %s", name,
domain->domain_id);
ctx = ERR_PTR(-EEXIST);
}
mutex_unlock(&erofs_domain_cookies_lock);
return ctx;
}
ctx = erofs_domain_init_cookie(sb, name, flags);
mutex_unlock(&erofs_domain_cookies_lock);
return ctx;
}
struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
char *name,
unsigned int flags)
{
if (EROFS_SB(sb)->domain_id)
return erofs_domain_register_cookie(sb, name, flags);
return erofs_fscache_acquire_cookie(sb, name, flags);
}
void erofs_fscache_unregister_cookie(struct erofs_fscache *ctx)
{
struct erofs_domain *domain = NULL;
if (!ctx)
return;
if (!ctx->domain)
return erofs_fscache_relinquish_cookie(ctx);
mutex_lock(&erofs_domain_cookies_lock);
if (refcount_dec_and_test(&ctx->ref)) {
domain = ctx->domain;
list_del(&ctx->node);
erofs_fscache_relinquish_cookie(ctx);
}
mutex_unlock(&erofs_domain_cookies_lock);
if (domain)
erofs_fscache_domain_put(domain);
}
int erofs_fscache_register_fs(struct super_block *sb)
{
int ret;
struct erofs_sb_info *sbi = EROFS_SB(sb);
struct erofs_fscache *fscache;
unsigned int flags = 0;
if (sbi->domain_id)
ret = erofs_fscache_register_domain(sb);
else
ret = erofs_fscache_register_volume(sb);
if (ret)
return ret;
/*
* When shared domain is enabled, using NEED_NOEXIST to guarantee
* the primary data blob (aka fsid) is unique in the shared domain.
*
* For non-shared-domain case, fscache_acquire_volume() invoked by
* erofs_fscache_register_volume() has already guaranteed
* the uniqueness of primary data blob.
*
* Acquired domain/volume will be relinquished in kill_sb() on error.
*/
if (sbi->domain_id)
flags |= EROFS_REG_COOKIE_NEED_NOEXIST;
fscache = erofs_fscache_register_cookie(sb, sbi->fsid, flags);
if (IS_ERR(fscache))
return PTR_ERR(fscache);
sbi->s_fscache = fscache;
return 0;
}
void erofs_fscache_unregister_fs(struct super_block *sb)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
erofs_fscache_unregister_cookie(sbi->s_fscache);
if (sbi->domain)
erofs_fscache_domain_put(sbi->domain);
else
fscache_relinquish_volume(sbi->volume, NULL, false);
sbi->s_fscache = NULL;
sbi->volume = NULL;
sbi->domain = NULL;
}
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