1 files changed, 612 insertions, 0 deletions

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
new file mode 100644
index 000000000..87ff35bff
--- /dev/null
+++ b/fs/erofs/fscache.c
@@ -0,0 +1,612 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2022, Alibaba Cloud
+ * Copyright (C) 2022, Bytedance Inc. All rights reserved.
+ */
+#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;
+
+struct erofs_fscache_request {
+	struct erofs_fscache_request *primary;
+	struct netfs_cache_resources cache_resources;
+	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 struct erofs_fscache_request *erofs_fscache_req_alloc(struct address_space *mapping,
+					     loff_t start, size_t len)
+{
+	struct erofs_fscache_request *req;
+
+	req = kzalloc(sizeof(struct erofs_fscache_request), GFP_KERNEL);
+	if (!req)
+		return ERR_PTR(-ENOMEM);
+
+	req->mapping = mapping;
+	req->start   = start;
+	req->len     = len;
+	refcount_set(&req->ref, 1);
+
+	return req;
+}
+
+static struct erofs_fscache_request *erofs_fscache_req_chain(struct erofs_fscache_request *primary,
+					     size_t len)
+{
+	struct erofs_fscache_request *req;
+
+	/* use primary request for the first submission */
+	if (!primary->submitted) {
+		refcount_inc(&primary->ref);
+		return primary;
+	}
+
+	req = erofs_fscache_req_alloc(primary->mapping,
+			primary->start + primary->submitted, len);
+	if (!IS_ERR(req)) {
+		req->primary = primary;
+		refcount_inc(&primary->ref);
+	}
+	return req;
+}
+
+static void erofs_fscache_req_complete(struct erofs_fscache_request *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_request *req)
+{
+	if (refcount_dec_and_test(&req->ref)) {
+		if (req->cache_resources.ops)
+			req->cache_resources.ops->end_operation(&req->cache_resources);
+		if (!req->primary)
+			erofs_fscache_req_complete(req);
+		else
+			erofs_fscache_req_put(req->primary);
+		kfree(req);
+	}
+}
+
+static void erofs_fscache_subreq_complete(void *priv,
+		ssize_t transferred_or_error, bool was_async)
+{
+	struct erofs_fscache_request *req = priv;
+
+	if (IS_ERR_VALUE(transferred_or_error)) {
+		if (req->primary)
+			req->primary->error = transferred_or_error;
+		else
+			req->error = transferred_or_error;
+	}
+	erofs_fscache_req_put(req);
+}
+
+/*
+ * Read data from fscache (cookie, pstart, len), and fill the read data into
+ * page cache described by (req->mapping, lstart, len). @pstart describeis the
+ * start physical address in the cache file.
+ */
+static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
+		struct erofs_fscache_request *req, loff_t pstart, size_t len)
+{
+	enum netfs_io_source source;
+	struct super_block *sb = req->mapping->host->i_sb;
+	struct netfs_cache_resources *cres = &req->cache_resources;
+	struct iov_iter iter;
+	loff_t lstart = req->start + req->submitted;
+	size_t done = 0;
+	int ret;
+
+	DBG_BUGON(len > req->len - req->submitted);
+
+	ret = fscache_begin_read_operation(cres, cookie);
+	if (ret)
+		return ret;
+
+	while (done < len) {
+		loff_t sstart = pstart + done;
+		size_t slen = len - done;
+		unsigned long flags = 1 << NETFS_SREQ_ONDEMAND;
+
+		source = cres->ops->prepare_ondemand_read(cres,
+				sstart, &slen, LLONG_MAX, &flags, 0);
+		if (WARN_ON(slen == 0))
+			source = NETFS_INVALID_READ;
+		if (source != NETFS_READ_FROM_CACHE) {
+			erofs_err(sb, "failed to fscache prepare_read (source %d)", source);
+			return -EIO;
+		}
+
+		refcount_inc(&req->ref);
+		iov_iter_xarray(&iter, ITER_DEST, &req->mapping->i_pages,
+				lstart + done, slen);
+
+		ret = fscache_read(cres, sstart, &iter, NETFS_READ_HOLE_FAIL,
+				   erofs_fscache_subreq_complete, req);
+		if (ret == -EIOCBQUEUED)
+			ret = 0;
+		if (ret) {
+			erofs_err(sb, "failed to fscache_read (ret %d)", ret);
+			return ret;
+		}
+
+		done += slen;
+	}
+	DBG_BUGON(done != len);
+	return 0;
+}
+
+static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
+{
+	int ret;
+	struct erofs_fscache *ctx = folio_mapping(folio)->host->i_private;
+	struct erofs_fscache_request *req;
+
+	req = erofs_fscache_req_alloc(folio_mapping(folio),
+				folio_pos(folio), folio_size(folio));
+	if (IS_ERR(req)) {
+		folio_unlock(folio);
+		return PTR_ERR(req);
+	}
+
+	ret = erofs_fscache_read_folios_async(ctx->cookie, req,
+				folio_pos(folio), folio_size(folio));
+	if (ret)
+		req->error = ret;
+
+	erofs_fscache_req_put(req);
+	return ret;
+}
+
+static int erofs_fscache_data_read_slice(struct erofs_fscache_request *primary)
+{
+	struct address_space *mapping = primary->mapping;
+	struct inode *inode = mapping->host;
+	struct super_block *sb = inode->i_sb;
+	struct erofs_fscache_request *req;
+	struct erofs_map_blocks map;
+	struct erofs_map_dev mdev;
+	struct iov_iter iter;
+	loff_t pos = primary->start + primary->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;
+		erofs_blk_t blknr;
+		size_t offset, size;
+		void *src;
+
+		/* For tail packing layout, the offset may be non-zero. */
+		offset = erofs_blkoff(sb, map.m_pa);
+		blknr = erofs_blknr(sb, map.m_pa);
+		size = map.m_llen;
+
+		src = erofs_read_metabuf(&buf, sb, blknr, 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 + offset, size, &iter) != size) {
+			erofs_put_metabuf(&buf);
+			return -EFAULT;
+		}
+		iov_iter_zero(PAGE_SIZE - size, &iter);
+		erofs_put_metabuf(&buf);
+		primary->submitted += PAGE_SIZE;
+		return 0;
+	}
+
+	count = primary->len - primary->submitted;
+	if (!(map.m_flags & EROFS_MAP_MAPPED)) {
+		iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, count);
+		iov_iter_zero(count, &iter);
+		primary->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;
+
+	req = erofs_fscache_req_chain(primary, count);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	ret = erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
+			req, mdev.m_pa + (pos - map.m_la), count);
+	erofs_fscache_req_put(req);
+	primary->submitted += count;
+	return ret;
+}
+
+static int erofs_fscache_data_read(struct erofs_fscache_request *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_request *req;
+	int ret;
+
+	req = erofs_fscache_req_alloc(folio_mapping(folio),
+			folio_pos(folio), folio_size(folio));
+	if (IS_ERR(req)) {
+		folio_unlock(folio);
+		return PTR_ERR(req);
+	}
+
+	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_request *req;
+
+	if (!readahead_count(rac))
+		return;
+
+	req = erofs_fscache_req_alloc(rac->mapping,
+			readahead_pos(rac), readahead_length(rac));
+	if (IS_ERR(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) {
+		erofs_pseudo_mnt = kern_mount(&erofs_fs_type);
+		if (IS_ERR(erofs_pseudo_mnt)) {
+			err = PTR_ERR(erofs_pseudo_mnt);
+			goto out;
+		}
+	}
+
+	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_NOFS);
+	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;
+}