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37020bbb71
The xarray iteration only holds the RCU read lock and thus may encounter
XA_RETRY_ENTRY if there's process modifying the xarray concurrently.
This will cause oops when referring to the invalid entry.
Fix this by adding the missing xas_retry(), which will make the
iteration wind back to the root node if XA_RETRY_ENTRY is encountered.
Fixes: d435d53228
("erofs: change to use asynchronous io for fscache readpage/readahead")
Suggested-by: David Howells <dhowells@redhat.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221114121943.29987-1-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
682 lines
16 KiB
C
682 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2022, Alibaba Cloud
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* Copyright (C) 2022, Bytedance Inc. All rights reserved.
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*/
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#include <linux/fscache.h>
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#include "internal.h"
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static DEFINE_MUTEX(erofs_domain_list_lock);
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static DEFINE_MUTEX(erofs_domain_cookies_lock);
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static LIST_HEAD(erofs_domain_list);
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static struct vfsmount *erofs_pseudo_mnt;
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static struct netfs_io_request *erofs_fscache_alloc_request(struct address_space *mapping,
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loff_t start, size_t len)
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{
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struct netfs_io_request *rreq;
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rreq = kzalloc(sizeof(struct netfs_io_request), GFP_KERNEL);
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if (!rreq)
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return ERR_PTR(-ENOMEM);
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rreq->start = start;
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rreq->len = len;
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rreq->mapping = mapping;
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rreq->inode = mapping->host;
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INIT_LIST_HEAD(&rreq->subrequests);
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refcount_set(&rreq->ref, 1);
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return rreq;
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}
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static void erofs_fscache_put_request(struct netfs_io_request *rreq)
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{
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if (!refcount_dec_and_test(&rreq->ref))
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return;
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if (rreq->cache_resources.ops)
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rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
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kfree(rreq);
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}
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static void erofs_fscache_put_subrequest(struct netfs_io_subrequest *subreq)
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{
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if (!refcount_dec_and_test(&subreq->ref))
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return;
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erofs_fscache_put_request(subreq->rreq);
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kfree(subreq);
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}
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static void erofs_fscache_clear_subrequests(struct netfs_io_request *rreq)
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{
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struct netfs_io_subrequest *subreq;
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while (!list_empty(&rreq->subrequests)) {
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subreq = list_first_entry(&rreq->subrequests,
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struct netfs_io_subrequest, rreq_link);
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list_del(&subreq->rreq_link);
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erofs_fscache_put_subrequest(subreq);
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}
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}
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static void erofs_fscache_rreq_unlock_folios(struct netfs_io_request *rreq)
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{
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struct netfs_io_subrequest *subreq;
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struct folio *folio;
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unsigned int iopos = 0;
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pgoff_t start_page = rreq->start / PAGE_SIZE;
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pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
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bool subreq_failed = false;
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XA_STATE(xas, &rreq->mapping->i_pages, start_page);
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subreq = list_first_entry(&rreq->subrequests,
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struct netfs_io_subrequest, rreq_link);
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subreq_failed = (subreq->error < 0);
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rcu_read_lock();
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xas_for_each(&xas, folio, last_page) {
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unsigned int pgpos, pgend;
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bool pg_failed = false;
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if (xas_retry(&xas, folio))
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continue;
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pgpos = (folio_index(folio) - start_page) * PAGE_SIZE;
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pgend = pgpos + folio_size(folio);
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for (;;) {
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if (!subreq) {
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pg_failed = true;
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break;
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}
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pg_failed |= subreq_failed;
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if (pgend < iopos + subreq->len)
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break;
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iopos += subreq->len;
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if (!list_is_last(&subreq->rreq_link,
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&rreq->subrequests)) {
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subreq = list_next_entry(subreq, rreq_link);
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subreq_failed = (subreq->error < 0);
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} else {
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subreq = NULL;
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subreq_failed = false;
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}
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if (pgend == iopos)
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break;
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}
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if (!pg_failed)
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folio_mark_uptodate(folio);
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folio_unlock(folio);
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}
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rcu_read_unlock();
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}
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static void erofs_fscache_rreq_complete(struct netfs_io_request *rreq)
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{
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erofs_fscache_rreq_unlock_folios(rreq);
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erofs_fscache_clear_subrequests(rreq);
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erofs_fscache_put_request(rreq);
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}
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static void erofc_fscache_subreq_complete(void *priv,
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ssize_t transferred_or_error, bool was_async)
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{
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struct netfs_io_subrequest *subreq = priv;
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struct netfs_io_request *rreq = subreq->rreq;
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if (IS_ERR_VALUE(transferred_or_error))
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subreq->error = transferred_or_error;
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if (atomic_dec_and_test(&rreq->nr_outstanding))
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erofs_fscache_rreq_complete(rreq);
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erofs_fscache_put_subrequest(subreq);
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}
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/*
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* Read data from fscache and fill the read data into page cache described by
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* @rreq, which shall be both aligned with PAGE_SIZE. @pstart describes
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* the start physical address in the cache file.
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*/
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static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
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struct netfs_io_request *rreq, loff_t pstart)
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{
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enum netfs_io_source source;
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struct super_block *sb = rreq->mapping->host->i_sb;
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struct netfs_io_subrequest *subreq;
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struct netfs_cache_resources *cres = &rreq->cache_resources;
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struct iov_iter iter;
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loff_t start = rreq->start;
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size_t len = rreq->len;
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size_t done = 0;
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int ret;
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atomic_set(&rreq->nr_outstanding, 1);
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ret = fscache_begin_read_operation(cres, cookie);
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if (ret)
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goto out;
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while (done < len) {
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subreq = kzalloc(sizeof(struct netfs_io_subrequest),
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GFP_KERNEL);
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if (subreq) {
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INIT_LIST_HEAD(&subreq->rreq_link);
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refcount_set(&subreq->ref, 2);
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subreq->rreq = rreq;
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refcount_inc(&rreq->ref);
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} else {
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ret = -ENOMEM;
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goto out;
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}
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subreq->start = pstart + done;
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subreq->len = len - done;
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subreq->flags = 1 << NETFS_SREQ_ONDEMAND;
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list_add_tail(&subreq->rreq_link, &rreq->subrequests);
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source = cres->ops->prepare_read(subreq, LLONG_MAX);
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if (WARN_ON(subreq->len == 0))
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source = NETFS_INVALID_READ;
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if (source != NETFS_READ_FROM_CACHE) {
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erofs_err(sb, "failed to fscache prepare_read (source %d)",
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source);
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ret = -EIO;
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subreq->error = ret;
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erofs_fscache_put_subrequest(subreq);
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goto out;
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}
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atomic_inc(&rreq->nr_outstanding);
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iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
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start + done, subreq->len);
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ret = fscache_read(cres, subreq->start, &iter,
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NETFS_READ_HOLE_FAIL,
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erofc_fscache_subreq_complete, subreq);
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if (ret == -EIOCBQUEUED)
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ret = 0;
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if (ret) {
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erofs_err(sb, "failed to fscache_read (ret %d)", ret);
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goto out;
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}
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done += subreq->len;
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}
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out:
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if (atomic_dec_and_test(&rreq->nr_outstanding))
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erofs_fscache_rreq_complete(rreq);
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return ret;
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}
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static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
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{
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int ret;
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struct super_block *sb = folio_mapping(folio)->host->i_sb;
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struct netfs_io_request *rreq;
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struct erofs_map_dev mdev = {
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.m_deviceid = 0,
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.m_pa = folio_pos(folio),
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};
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ret = erofs_map_dev(sb, &mdev);
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if (ret)
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goto out;
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rreq = erofs_fscache_alloc_request(folio_mapping(folio),
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folio_pos(folio), folio_size(folio));
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if (IS_ERR(rreq)) {
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ret = PTR_ERR(rreq);
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goto out;
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}
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return erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
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rreq, mdev.m_pa);
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out:
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folio_unlock(folio);
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return ret;
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}
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/*
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* Read into page cache in the range described by (@pos, @len).
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*
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* On return, the caller is responsible for page unlocking if the output @unlock
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* is true, or the callee will take this responsibility through netfs_io_request
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* interface.
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*
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* The return value is the number of bytes successfully handled, or negative
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* error code on failure. The only exception is that, the length of the range
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* instead of the error code is returned on failure after netfs_io_request is
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* allocated, so that .readahead() could advance rac accordingly.
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*/
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static int erofs_fscache_data_read(struct address_space *mapping,
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loff_t pos, size_t len, bool *unlock)
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{
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struct inode *inode = mapping->host;
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struct super_block *sb = inode->i_sb;
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struct netfs_io_request *rreq;
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struct erofs_map_blocks map;
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struct erofs_map_dev mdev;
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struct iov_iter iter;
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size_t count;
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int ret;
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*unlock = true;
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map.m_la = pos;
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ret = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
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if (ret)
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return ret;
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if (map.m_flags & EROFS_MAP_META) {
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struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
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erofs_blk_t blknr;
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size_t offset, size;
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void *src;
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/* For tail packing layout, the offset may be non-zero. */
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offset = erofs_blkoff(map.m_pa);
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blknr = erofs_blknr(map.m_pa);
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size = map.m_llen;
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src = erofs_read_metabuf(&buf, sb, blknr, EROFS_KMAP);
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if (IS_ERR(src))
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return PTR_ERR(src);
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iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, PAGE_SIZE);
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if (copy_to_iter(src + offset, size, &iter) != size) {
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erofs_put_metabuf(&buf);
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return -EFAULT;
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}
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iov_iter_zero(PAGE_SIZE - size, &iter);
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erofs_put_metabuf(&buf);
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return PAGE_SIZE;
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}
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if (!(map.m_flags & EROFS_MAP_MAPPED)) {
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count = len;
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iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, count);
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iov_iter_zero(count, &iter);
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return count;
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}
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count = min_t(size_t, map.m_llen - (pos - map.m_la), len);
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DBG_BUGON(!count || count % PAGE_SIZE);
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mdev = (struct erofs_map_dev) {
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.m_deviceid = map.m_deviceid,
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.m_pa = map.m_pa,
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};
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ret = erofs_map_dev(sb, &mdev);
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if (ret)
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return ret;
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rreq = erofs_fscache_alloc_request(mapping, pos, count);
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if (IS_ERR(rreq))
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return PTR_ERR(rreq);
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*unlock = false;
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erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
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rreq, mdev.m_pa + (pos - map.m_la));
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return count;
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}
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static int erofs_fscache_read_folio(struct file *file, struct folio *folio)
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{
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bool unlock;
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int ret;
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DBG_BUGON(folio_size(folio) != EROFS_BLKSIZ);
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ret = erofs_fscache_data_read(folio_mapping(folio), folio_pos(folio),
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folio_size(folio), &unlock);
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if (unlock) {
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if (ret > 0)
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folio_mark_uptodate(folio);
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folio_unlock(folio);
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}
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return ret < 0 ? ret : 0;
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}
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static void erofs_fscache_readahead(struct readahead_control *rac)
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{
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struct folio *folio;
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size_t len, done = 0;
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loff_t start, pos;
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bool unlock;
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int ret, size;
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if (!readahead_count(rac))
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return;
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start = readahead_pos(rac);
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len = readahead_length(rac);
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do {
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pos = start + done;
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ret = erofs_fscache_data_read(rac->mapping, pos,
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len - done, &unlock);
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if (ret <= 0)
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return;
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size = ret;
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while (size) {
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folio = readahead_folio(rac);
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size -= folio_size(folio);
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if (unlock) {
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folio_mark_uptodate(folio);
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folio_unlock(folio);
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}
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}
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} while ((done += ret) < len);
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}
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static const struct address_space_operations erofs_fscache_meta_aops = {
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.read_folio = erofs_fscache_meta_read_folio,
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};
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const struct address_space_operations erofs_fscache_access_aops = {
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.read_folio = erofs_fscache_read_folio,
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.readahead = erofs_fscache_readahead,
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};
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static void erofs_fscache_domain_put(struct erofs_domain *domain)
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{
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if (!domain)
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return;
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mutex_lock(&erofs_domain_list_lock);
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if (refcount_dec_and_test(&domain->ref)) {
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list_del(&domain->list);
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if (list_empty(&erofs_domain_list)) {
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kern_unmount(erofs_pseudo_mnt);
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erofs_pseudo_mnt = NULL;
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}
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mutex_unlock(&erofs_domain_list_lock);
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fscache_relinquish_volume(domain->volume, NULL, false);
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kfree(domain->domain_id);
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kfree(domain);
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return;
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}
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mutex_unlock(&erofs_domain_list_lock);
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}
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static int erofs_fscache_register_volume(struct super_block *sb)
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{
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struct erofs_sb_info *sbi = EROFS_SB(sb);
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char *domain_id = sbi->domain_id;
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struct fscache_volume *volume;
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char *name;
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int ret = 0;
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name = kasprintf(GFP_KERNEL, "erofs,%s",
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domain_id ? domain_id : sbi->fsid);
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if (!name)
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return -ENOMEM;
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volume = fscache_acquire_volume(name, NULL, NULL, 0);
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if (IS_ERR_OR_NULL(volume)) {
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erofs_err(sb, "failed to register volume for %s", name);
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ret = volume ? PTR_ERR(volume) : -EOPNOTSUPP;
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volume = NULL;
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}
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sbi->volume = volume;
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kfree(name);
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return ret;
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}
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static int erofs_fscache_init_domain(struct super_block *sb)
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{
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int err;
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struct erofs_domain *domain;
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struct erofs_sb_info *sbi = EROFS_SB(sb);
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domain = kzalloc(sizeof(struct erofs_domain), GFP_KERNEL);
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if (!domain)
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return -ENOMEM;
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domain->domain_id = kstrdup(sbi->domain_id, GFP_KERNEL);
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if (!domain->domain_id) {
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kfree(domain);
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return -ENOMEM;
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}
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err = erofs_fscache_register_volume(sb);
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if (err)
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goto out;
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if (!erofs_pseudo_mnt) {
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erofs_pseudo_mnt = kern_mount(&erofs_fs_type);
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if (IS_ERR(erofs_pseudo_mnt)) {
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err = PTR_ERR(erofs_pseudo_mnt);
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goto out;
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}
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}
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domain->volume = sbi->volume;
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refcount_set(&domain->ref, 1);
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list_add(&domain->list, &erofs_domain_list);
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sbi->domain = domain;
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return 0;
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out:
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kfree(domain->domain_id);
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kfree(domain);
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return err;
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}
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static int erofs_fscache_register_domain(struct super_block *sb)
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{
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int err;
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struct erofs_domain *domain;
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struct erofs_sb_info *sbi = EROFS_SB(sb);
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mutex_lock(&erofs_domain_list_lock);
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list_for_each_entry(domain, &erofs_domain_list, list) {
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if (!strcmp(domain->domain_id, sbi->domain_id)) {
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sbi->domain = domain;
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sbi->volume = domain->volume;
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refcount_inc(&domain->ref);
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mutex_unlock(&erofs_domain_list_lock);
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return 0;
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}
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}
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err = erofs_fscache_init_domain(sb);
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mutex_unlock(&erofs_domain_list_lock);
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return err;
|
|
}
|
|
|
|
static
|
|
struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
|
|
char *name, bool need_inode)
|
|
{
|
|
struct fscache_volume *volume = EROFS_SB(sb)->volume;
|
|
struct erofs_fscache *ctx;
|
|
struct fscache_cookie *cookie;
|
|
int ret;
|
|
|
|
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
|
|
if (!ctx)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
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);
|
|
ctx->cookie = cookie;
|
|
|
|
if (need_inode) {
|
|
struct inode *const inode = new_inode(sb);
|
|
|
|
if (!inode) {
|
|
erofs_err(sb, "failed to get anon inode for %s", name);
|
|
ret = -ENOMEM;
|
|
goto err_cookie;
|
|
}
|
|
|
|
set_nlink(inode, 1);
|
|
inode->i_size = OFFSET_MAX;
|
|
inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
|
|
mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
|
|
|
|
ctx->inode = inode;
|
|
}
|
|
|
|
return ctx;
|
|
|
|
err_cookie:
|
|
fscache_unuse_cookie(ctx->cookie, NULL, NULL);
|
|
fscache_relinquish_cookie(ctx->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_fscache_domain_init_cookie(struct super_block *sb,
|
|
char *name, bool need_inode)
|
|
{
|
|
int err;
|
|
struct inode *inode;
|
|
struct erofs_fscache *ctx;
|
|
struct erofs_domain *domain = EROFS_SB(sb)->domain;
|
|
|
|
ctx = erofs_fscache_acquire_cookie(sb, name, need_inode);
|
|
if (IS_ERR(ctx))
|
|
return ctx;
|
|
|
|
ctx->name = kstrdup(name, GFP_KERNEL);
|
|
if (!ctx->name) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
inode = new_inode(erofs_pseudo_mnt->mnt_sb);
|
|
if (!inode) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
ctx->domain = domain;
|
|
ctx->anon_inode = inode;
|
|
inode->i_private = ctx;
|
|
refcount_inc(&domain->ref);
|
|
return ctx;
|
|
out:
|
|
erofs_fscache_relinquish_cookie(ctx);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
static
|
|
struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
|
|
char *name, bool need_inode)
|
|
{
|
|
struct inode *inode;
|
|
struct erofs_fscache *ctx;
|
|
struct erofs_domain *domain = EROFS_SB(sb)->domain;
|
|
struct super_block *psb = erofs_pseudo_mnt->mnt_sb;
|
|
|
|
mutex_lock(&erofs_domain_cookies_lock);
|
|
spin_lock(&psb->s_inode_list_lock);
|
|
list_for_each_entry(inode, &psb->s_inodes, i_sb_list) {
|
|
ctx = inode->i_private;
|
|
if (!ctx || ctx->domain != domain || strcmp(ctx->name, name))
|
|
continue;
|
|
igrab(inode);
|
|
spin_unlock(&psb->s_inode_list_lock);
|
|
mutex_unlock(&erofs_domain_cookies_lock);
|
|
return ctx;
|
|
}
|
|
spin_unlock(&psb->s_inode_list_lock);
|
|
ctx = erofs_fscache_domain_init_cookie(sb, name, need_inode);
|
|
mutex_unlock(&erofs_domain_cookies_lock);
|
|
return ctx;
|
|
}
|
|
|
|
struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
|
|
char *name, bool need_inode)
|
|
{
|
|
if (EROFS_SB(sb)->domain_id)
|
|
return erofs_domain_register_cookie(sb, name, need_inode);
|
|
return erofs_fscache_acquire_cookie(sb, name, need_inode);
|
|
}
|
|
|
|
void erofs_fscache_unregister_cookie(struct erofs_fscache *ctx)
|
|
{
|
|
bool drop;
|
|
struct erofs_domain *domain;
|
|
|
|
if (!ctx)
|
|
return;
|
|
domain = ctx->domain;
|
|
if (domain) {
|
|
mutex_lock(&erofs_domain_cookies_lock);
|
|
drop = atomic_read(&ctx->anon_inode->i_count) == 1;
|
|
iput(ctx->anon_inode);
|
|
mutex_unlock(&erofs_domain_cookies_lock);
|
|
if (!drop)
|
|
return;
|
|
}
|
|
|
|
erofs_fscache_relinquish_cookie(ctx);
|
|
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;
|
|
|
|
if (sbi->domain_id)
|
|
ret = erofs_fscache_register_domain(sb);
|
|
else
|
|
ret = erofs_fscache_register_volume(sb);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/* acquired domain/volume will be relinquished in kill_sb() on error */
|
|
fscache = erofs_fscache_register_cookie(sb, sbi->fsid, true);
|
|
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;
|
|
}
|