linux-stable/fs/erofs/fscache.c
Linus Torvalds 8171acb8bc Changes since last update:
- Leave compressed inodes unsupported in fscache mode for now;
 
  - Avoid crash when using tracepoint cachefiles_prep_read;
 
  - Fix `backmost' behavior due to a recent cleanup;
 
  - Update documentation for better description of recent new features;
 
  - Several decompression cleanups w/o logical change.
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Merge tag 'erofs-for-5.19-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull more erofs updates from Gao Xiang:
 "This is a follow-up to the main updates, including some fixes of
  fscache mode related to compressed inodes and a cachefiles tracepoint.
  There is also a patch to fix an unexpected decompression strategy
  change due to a cleanup in the past. All the fixes are quite small.

  Apart from these, documentation is also updated for a better
  description of recent new features.

  In addition, this has some trivial cleanups without actual code logic
  changes, so I could have a more recent codebase to work on folios and
  avoiding the PG_error page flag for the next cycle.

  Summary:

   - Leave compressed inodes unsupported in fscache mode for now

   - Avoid crash when using tracepoint cachefiles_prep_read

   - Fix `backmost' behavior due to a recent cleanup

   - Update documentation for better description of recent new features

   - Several decompression cleanups w/o logical change"

* tag 'erofs-for-5.19-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: fix 'backmost' member of z_erofs_decompress_frontend
  erofs: simplify z_erofs_pcluster_readmore()
  erofs: get rid of label `restart_now'
  erofs: get rid of `struct z_erofs_collection'
  erofs: update documentation
  erofs: fix crash when enable tracepoint cachefiles_prep_read
  erofs: leave compressed inodes unsupported in fscache mode for now
2022-06-01 11:54:29 -07:00

520 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2022, Alibaba Cloud
*/
#include <linux/fscache.h>
#include "internal.h"
static struct netfs_io_request *erofs_fscache_alloc_request(struct address_space *mapping,
loff_t start, size_t len)
{
struct netfs_io_request *rreq;
rreq = kzalloc(sizeof(struct netfs_io_request), GFP_KERNEL);
if (!rreq)
return ERR_PTR(-ENOMEM);
rreq->start = start;
rreq->len = len;
rreq->mapping = mapping;
rreq->inode = mapping->host;
INIT_LIST_HEAD(&rreq->subrequests);
refcount_set(&rreq->ref, 1);
return rreq;
}
static void erofs_fscache_put_request(struct netfs_io_request *rreq)
{
if (!refcount_dec_and_test(&rreq->ref))
return;
if (rreq->cache_resources.ops)
rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
kfree(rreq);
}
static void erofs_fscache_put_subrequest(struct netfs_io_subrequest *subreq)
{
if (!refcount_dec_and_test(&subreq->ref))
return;
erofs_fscache_put_request(subreq->rreq);
kfree(subreq);
}
static void erofs_fscache_clear_subrequests(struct netfs_io_request *rreq)
{
struct netfs_io_subrequest *subreq;
while (!list_empty(&rreq->subrequests)) {
subreq = list_first_entry(&rreq->subrequests,
struct netfs_io_subrequest, rreq_link);
list_del(&subreq->rreq_link);
erofs_fscache_put_subrequest(subreq);
}
}
static void erofs_fscache_rreq_unlock_folios(struct netfs_io_request *rreq)
{
struct netfs_io_subrequest *subreq;
struct folio *folio;
unsigned int iopos = 0;
pgoff_t start_page = rreq->start / PAGE_SIZE;
pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
bool subreq_failed = false;
XA_STATE(xas, &rreq->mapping->i_pages, start_page);
subreq = list_first_entry(&rreq->subrequests,
struct netfs_io_subrequest, rreq_link);
subreq_failed = (subreq->error < 0);
rcu_read_lock();
xas_for_each(&xas, folio, last_page) {
unsigned int pgpos =
(folio_index(folio) - start_page) * PAGE_SIZE;
unsigned int pgend = pgpos + folio_size(folio);
bool pg_failed = false;
for (;;) {
if (!subreq) {
pg_failed = true;
break;
}
pg_failed |= subreq_failed;
if (pgend < iopos + subreq->len)
break;
iopos += subreq->len;
if (!list_is_last(&subreq->rreq_link,
&rreq->subrequests)) {
subreq = list_next_entry(subreq, rreq_link);
subreq_failed = (subreq->error < 0);
} else {
subreq = NULL;
subreq_failed = false;
}
if (pgend == iopos)
break;
}
if (!pg_failed)
folio_mark_uptodate(folio);
folio_unlock(folio);
}
rcu_read_unlock();
}
static void erofs_fscache_rreq_complete(struct netfs_io_request *rreq)
{
erofs_fscache_rreq_unlock_folios(rreq);
erofs_fscache_clear_subrequests(rreq);
erofs_fscache_put_request(rreq);
}
static void erofc_fscache_subreq_complete(void *priv,
ssize_t transferred_or_error, bool was_async)
{
struct netfs_io_subrequest *subreq = priv;
struct netfs_io_request *rreq = subreq->rreq;
if (IS_ERR_VALUE(transferred_or_error))
subreq->error = transferred_or_error;
if (atomic_dec_and_test(&rreq->nr_outstanding))
erofs_fscache_rreq_complete(rreq);
erofs_fscache_put_subrequest(subreq);
}
/*
* Read data from fscache and fill the read data into page cache described by
* @rreq, which shall be both aligned with PAGE_SIZE. @pstart describes
* the start physical address in the cache file.
*/
static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
struct netfs_io_request *rreq, loff_t pstart)
{
enum netfs_io_source source;
struct super_block *sb = rreq->mapping->host->i_sb;
struct netfs_io_subrequest *subreq;
struct netfs_cache_resources *cres = &rreq->cache_resources;
struct iov_iter iter;
loff_t start = rreq->start;
size_t len = rreq->len;
size_t done = 0;
int ret;
atomic_set(&rreq->nr_outstanding, 1);
ret = fscache_begin_read_operation(cres, cookie);
if (ret)
goto out;
while (done < len) {
subreq = kzalloc(sizeof(struct netfs_io_subrequest),
GFP_KERNEL);
if (subreq) {
INIT_LIST_HEAD(&subreq->rreq_link);
refcount_set(&subreq->ref, 2);
subreq->rreq = rreq;
refcount_inc(&rreq->ref);
} else {
ret = -ENOMEM;
goto out;
}
subreq->start = pstart + done;
subreq->len = len - done;
subreq->flags = 1 << NETFS_SREQ_ONDEMAND;
list_add_tail(&subreq->rreq_link, &rreq->subrequests);
source = cres->ops->prepare_read(subreq, LLONG_MAX);
if (WARN_ON(subreq->len == 0))
source = NETFS_INVALID_READ;
if (source != NETFS_READ_FROM_CACHE) {
erofs_err(sb, "failed to fscache prepare_read (source %d)",
source);
ret = -EIO;
subreq->error = ret;
erofs_fscache_put_subrequest(subreq);
goto out;
}
atomic_inc(&rreq->nr_outstanding);
iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
start + done, subreq->len);
ret = fscache_read(cres, subreq->start, &iter,
NETFS_READ_HOLE_FAIL,
erofc_fscache_subreq_complete, subreq);
if (ret == -EIOCBQUEUED)
ret = 0;
if (ret) {
erofs_err(sb, "failed to fscache_read (ret %d)", ret);
goto out;
}
done += subreq->len;
}
out:
if (atomic_dec_and_test(&rreq->nr_outstanding))
erofs_fscache_rreq_complete(rreq);
return ret;
}
static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
{
int ret;
struct super_block *sb = folio_mapping(folio)->host->i_sb;
struct netfs_io_request *rreq;
struct erofs_map_dev mdev = {
.m_deviceid = 0,
.m_pa = folio_pos(folio),
};
ret = erofs_map_dev(sb, &mdev);
if (ret)
goto out;
rreq = erofs_fscache_alloc_request(folio_mapping(folio),
folio_pos(folio), folio_size(folio));
if (IS_ERR(rreq))
goto out;
return erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
rreq, mdev.m_pa);
out:
folio_unlock(folio);
return ret;
}
static int erofs_fscache_read_folio_inline(struct folio *folio,
struct erofs_map_blocks *map)
{
struct super_block *sb = folio_mapping(folio)->host->i_sb;
struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
erofs_blk_t blknr;
size_t offset, len;
void *src, *dst;
/* For tail packing layout, the offset may be non-zero. */
offset = erofs_blkoff(map->m_pa);
blknr = erofs_blknr(map->m_pa);
len = map->m_llen;
src = erofs_read_metabuf(&buf, sb, blknr, EROFS_KMAP);
if (IS_ERR(src))
return PTR_ERR(src);
dst = kmap_local_folio(folio, 0);
memcpy(dst, src + offset, len);
memset(dst + len, 0, PAGE_SIZE - len);
kunmap_local(dst);
erofs_put_metabuf(&buf);
return 0;
}
static int erofs_fscache_read_folio(struct file *file, struct folio *folio)
{
struct inode *inode = folio_mapping(folio)->host;
struct super_block *sb = inode->i_sb;
struct erofs_map_blocks map;
struct erofs_map_dev mdev;
struct netfs_io_request *rreq;
erofs_off_t pos;
loff_t pstart;
int ret;
DBG_BUGON(folio_size(folio) != EROFS_BLKSIZ);
pos = folio_pos(folio);
map.m_la = pos;
ret = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
if (ret)
goto out_unlock;
if (!(map.m_flags & EROFS_MAP_MAPPED)) {
folio_zero_range(folio, 0, folio_size(folio));
goto out_uptodate;
}
if (map.m_flags & EROFS_MAP_META) {
ret = erofs_fscache_read_folio_inline(folio, &map);
goto out_uptodate;
}
mdev = (struct erofs_map_dev) {
.m_deviceid = map.m_deviceid,
.m_pa = map.m_pa,
};
ret = erofs_map_dev(sb, &mdev);
if (ret)
goto out_unlock;
rreq = erofs_fscache_alloc_request(folio_mapping(folio),
folio_pos(folio), folio_size(folio));
if (IS_ERR(rreq))
goto out_unlock;
pstart = mdev.m_pa + (pos - map.m_la);
return erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
rreq, pstart);
out_uptodate:
if (!ret)
folio_mark_uptodate(folio);
out_unlock:
folio_unlock(folio);
return ret;
}
static void erofs_fscache_advance_folios(struct readahead_control *rac,
size_t len, bool unlock)
{
while (len) {
struct folio *folio = readahead_folio(rac);
len -= folio_size(folio);
if (unlock) {
folio_mark_uptodate(folio);
folio_unlock(folio);
}
}
}
static void erofs_fscache_readahead(struct readahead_control *rac)
{
struct inode *inode = rac->mapping->host;
struct super_block *sb = inode->i_sb;
size_t len, count, done = 0;
erofs_off_t pos;
loff_t start, offset;
int ret;
if (!readahead_count(rac))
return;
start = readahead_pos(rac);
len = readahead_length(rac);
do {
struct erofs_map_blocks map;
struct erofs_map_dev mdev;
struct netfs_io_request *rreq;
pos = start + done;
map.m_la = pos;
ret = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
if (ret)
return;
offset = start + done;
count = min_t(size_t, map.m_llen - (pos - map.m_la),
len - done);
if (!(map.m_flags & EROFS_MAP_MAPPED)) {
struct iov_iter iter;
iov_iter_xarray(&iter, READ, &rac->mapping->i_pages,
offset, count);
iov_iter_zero(count, &iter);
erofs_fscache_advance_folios(rac, count, true);
ret = count;
continue;
}
if (map.m_flags & EROFS_MAP_META) {
struct folio *folio = readahead_folio(rac);
ret = erofs_fscache_read_folio_inline(folio, &map);
if (!ret) {
folio_mark_uptodate(folio);
ret = folio_size(folio);
}
folio_unlock(folio);
continue;
}
mdev = (struct erofs_map_dev) {
.m_deviceid = map.m_deviceid,
.m_pa = map.m_pa,
};
ret = erofs_map_dev(sb, &mdev);
if (ret)
return;
rreq = erofs_fscache_alloc_request(rac->mapping, offset, count);
if (IS_ERR(rreq))
return;
/*
* Drop the ref of folios here. Unlock them in
* rreq_unlock_folios() when rreq complete.
*/
erofs_fscache_advance_folios(rac, count, false);
ret = erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
rreq, mdev.m_pa + (pos - map.m_la));
if (!ret)
ret = count;
} while (ret > 0 && ((done += ret) < len));
}
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,
};
int erofs_fscache_register_cookie(struct super_block *sb,
struct erofs_fscache **fscache,
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 -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;
}
*fscache = ctx;
return 0;
err_cookie:
fscache_unuse_cookie(ctx->cookie, NULL, NULL);
fscache_relinquish_cookie(ctx->cookie, false);
ctx->cookie = NULL;
err:
kfree(ctx);
return ret;
}
void erofs_fscache_unregister_cookie(struct erofs_fscache **fscache)
{
struct erofs_fscache *ctx = *fscache;
if (!ctx)
return;
fscache_unuse_cookie(ctx->cookie, NULL, NULL);
fscache_relinquish_cookie(ctx->cookie, false);
ctx->cookie = NULL;
iput(ctx->inode);
ctx->inode = NULL;
kfree(ctx);
*fscache = NULL;
}
int erofs_fscache_register_fs(struct super_block *sb)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
struct fscache_volume *volume;
char *name;
int ret = 0;
name = kasprintf(GFP_KERNEL, "erofs,%s", sbi->opt.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;
}
void erofs_fscache_unregister_fs(struct super_block *sb)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
fscache_relinquish_volume(sbi->volume, NULL, false);
sbi->volume = NULL;
}