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Subject[PATCH v5 4/5] erofs: support inline data decompression
Date
From: Yue Hu <huyue2@yulong.com>

Currently, we have already support tail-packing inline for
uncompressed file, let's also implement this for compressed
files to save I/Os and storage space.

Different from normal pclusters, compressed data is available
in advance because of other metadata I/Os. Therefore, they
directly move into the bypass queue without extra I/O submission.

It's the last compression feature before folio/subpage support.

Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
changes since v4:
- fix original non-managed handling, found with LZMA
compression.

fs/erofs/zdata.c | 139 +++++++++++++++++++++++++++++++++--------------
fs/erofs/zdata.h | 24 +++++++-
2 files changed, 119 insertions(+), 44 deletions(-)

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index bc765d8a6dc2..49da3931b2e3 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -82,12 +82,13 @@ static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int nrpages)

static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
{
+ unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
int i;

for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;

- if (pcl->pclusterpages > pcs->maxpages)
+ if (pclusterpages > pcs->maxpages)
continue;

kmem_cache_free(pcs->slab, pcl);
@@ -298,6 +299,7 @@ int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
container_of(grp, struct z_erofs_pcluster, obj);
int i;

+ DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
/*
* refcount of workgroup is now freezed as 1,
* therefore no need to worry about available decompression users.
@@ -331,6 +333,7 @@ int erofs_try_to_free_cached_page(struct page *page)
if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
unsigned int i;

+ DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
for (i = 0; i < pcl->pclusterpages; ++i) {
if (pcl->compressed_pages[i] == page) {
WRITE_ONCE(pcl->compressed_pages[i], NULL);
@@ -458,6 +461,7 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
struct inode *inode,
struct erofs_map_blocks *map)
{
+ bool ztailpacking = map->m_flags & EROFS_MAP_META;
struct z_erofs_pcluster *pcl;
struct z_erofs_collection *cl;
struct erofs_workgroup *grp;
@@ -469,12 +473,12 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
}

/* no available pcluster, let's allocate one */
- pcl = z_erofs_alloc_pcluster(map->m_plen >> PAGE_SHIFT);
+ pcl = z_erofs_alloc_pcluster(ztailpacking ? 1 :
+ map->m_plen >> PAGE_SHIFT);
if (IS_ERR(pcl))
return PTR_ERR(pcl);

atomic_set(&pcl->obj.refcount, 1);
- pcl->obj.index = map->m_pa >> PAGE_SHIFT;
pcl->algorithmformat = map->m_algorithmformat;
pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
(map->m_flags & EROFS_MAP_FULL_MAPPED ?
@@ -494,16 +498,25 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
mutex_init(&cl->lock);
DBG_BUGON(!mutex_trylock(&cl->lock));

- grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
- if (IS_ERR(grp)) {
- err = PTR_ERR(grp);
- goto err_out;
- }
+ if (ztailpacking) {
+ pcl->obj.index = 0; /* which indicates ztailpacking */
+ pcl->pageofs_in = erofs_blkoff(map->m_pa);
+ pcl->tailpacking_size = map->m_plen;
+ } else {
+ pcl->obj.index = map->m_pa >> PAGE_SHIFT;

- if (grp != &pcl->obj) {
- clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
- err = -EEXIST;
- goto err_out;
+ grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
+ if (IS_ERR(grp)) {
+ err = PTR_ERR(grp);
+ goto err_out;
+ }
+
+ if (grp != &pcl->obj) {
+ clt->pcl = container_of(grp,
+ struct z_erofs_pcluster, obj);
+ err = -EEXIST;
+ goto err_out;
+ }
}
/* used to check tail merging loop due to corrupted images */
if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
@@ -532,17 +545,20 @@ static int z_erofs_collector_begin(struct z_erofs_collector *clt,
DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);

- if (!PAGE_ALIGNED(map->m_pa)) {
- DBG_BUGON(1);
- return -EINVAL;
+ if (map->m_flags & EROFS_MAP_META) {
+ if ((map->m_pa & ~PAGE_MASK) + map->m_plen > PAGE_SIZE) {
+ DBG_BUGON(1);
+ return -EFSCORRUPTED;
+ }
+ goto tailpacking;
}

grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
if (grp) {
clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
} else {
+tailpacking:
ret = z_erofs_register_collection(clt, inode, map);
-
if (!ret)
goto out;
if (ret != -EEXIST)
@@ -558,9 +574,9 @@ static int z_erofs_collector_begin(struct z_erofs_collector *clt,
out:
z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
clt->cl->pagevec, clt->cl->vcnt);
-
/* since file-backed online pages are traversed in reverse order */
- clt->icpage_ptr = clt->pcl->compressed_pages + clt->pcl->pclusterpages;
+ clt->icpage_ptr = clt->pcl->compressed_pages +
+ z_erofs_pclusterpages(clt->pcl);
return 0;
}

@@ -681,14 +697,33 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
if (err)
goto err_out;

- /* preload all compressed pages (maybe downgrade role if necessary) */
- if (should_alloc_managed_pages(fe, sbi->opt.cache_strategy, map->m_la))
- cache_strategy = TRYALLOC;
- else
- cache_strategy = DONTALLOC;
+ if (z_erofs_is_inline_pcluster(clt->pcl)) {
+ struct page *mpage;

- preload_compressed_pages(clt, MNGD_MAPPING(sbi),
- cache_strategy, pagepool);
+ mpage = erofs_get_meta_page(inode->i_sb,
+ erofs_blknr(map->m_pa));
+ if (IS_ERR(mpage)) {
+ err = PTR_ERR(mpage);
+ erofs_err(inode->i_sb,
+ "failed to get inline page, err %d", err);
+ goto err_out;
+ }
+ /* TODO: new subpage feature will get rid of it */
+ unlock_page(mpage);
+
+ WRITE_ONCE(clt->pcl->compressed_pages[0], mpage);
+ clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
+ } else {
+ /* preload all compressed pages (can change mode if needed) */
+ if (should_alloc_managed_pages(fe, sbi->opt.cache_strategy,
+ map->m_la))
+ cache_strategy = TRYALLOC;
+ else
+ cache_strategy = DONTALLOC;
+
+ preload_compressed_pages(clt, MNGD_MAPPING(sbi),
+ cache_strategy, pagepool);
+ }

hitted:
/*
@@ -844,6 +879,7 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
struct page **pagepool)
{
struct erofs_sb_info *const sbi = EROFS_SB(sb);
+ unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
struct z_erofs_pagevec_ctor ctor;
unsigned int i, inputsize, outputsize, llen, nr_pages;
struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
@@ -925,15 +961,20 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
overlapped = false;
compressed_pages = pcl->compressed_pages;

- for (i = 0; i < pcl->pclusterpages; ++i) {
+ for (i = 0; i < pclusterpages; ++i) {
unsigned int pagenr;

page = compressed_pages[i];
-
/* all compressed pages ought to be valid */
DBG_BUGON(!page);
- DBG_BUGON(z_erofs_page_is_invalidated(page));

+ if (z_erofs_is_inline_pcluster(pcl)) {
+ if (!PageUptodate(page))
+ err = -EIO;
+ continue;
+ }
+
+ DBG_BUGON(z_erofs_page_is_invalidated(page));
if (!z_erofs_is_shortlived_page(page)) {
if (erofs_page_is_managed(sbi, page)) {
if (!PageUptodate(page))
@@ -978,11 +1019,16 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
partial = true;
}

- inputsize = pcl->pclusterpages * PAGE_SIZE;
+ if (z_erofs_is_inline_pcluster(pcl))
+ inputsize = pcl->tailpacking_size;
+ else
+ inputsize = pclusterpages * PAGE_SIZE;
+
err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
.sb = sb,
.in = compressed_pages,
.out = pages,
+ .pageofs_in = pcl->pageofs_in,
.pageofs_out = cl->pageofs,
.inputsize = inputsize,
.outputsize = outputsize,
@@ -992,17 +1038,22 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
}, pagepool);

out:
- /* must handle all compressed pages before ending pages */
- for (i = 0; i < pcl->pclusterpages; ++i) {
- page = compressed_pages[i];
-
- if (erofs_page_is_managed(sbi, page))
- continue;
+ /* must handle all compressed pages before actual file pages */
+ if (z_erofs_is_inline_pcluster(pcl)) {
+ page = compressed_pages[0];
+ WRITE_ONCE(compressed_pages[0], NULL);
+ put_page(page);
+ } else {
+ for (i = 0; i < pclusterpages; ++i) {
+ page = compressed_pages[i];

- /* recycle all individual short-lived pages */
- (void)z_erofs_put_shortlivedpage(pagepool, page);
+ if (erofs_page_is_managed(sbi, page))
+ continue;

- WRITE_ONCE(compressed_pages[i], NULL);
+ /* recycle all individual short-lived pages */
+ (void)z_erofs_put_shortlivedpage(pagepool, page);
+ WRITE_ONCE(compressed_pages[i], NULL);
+ }
}

for (i = 0; i < nr_pages; ++i) {
@@ -1288,6 +1339,14 @@ static void z_erofs_submit_queue(struct super_block *sb,

pcl = container_of(owned_head, struct z_erofs_pcluster, next);

+ /* close the main owned chain at first */
+ owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
+ Z_EROFS_PCLUSTER_TAIL_CLOSED);
+ if (z_erofs_is_inline_pcluster(pcl)) {
+ move_to_bypass_jobqueue(pcl, qtail, owned_head);
+ continue;
+ }
+
/* no device id here, thus it will always succeed */
mdev = (struct erofs_map_dev) {
.m_pa = blknr_to_addr(pcl->obj.index),
@@ -1297,10 +1356,6 @@ static void z_erofs_submit_queue(struct super_block *sb,
cur = erofs_blknr(mdev.m_pa);
end = cur + pcl->pclusterpages;

- /* close the main owned chain at first */
- owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
- Z_EROFS_PCLUSTER_TAIL_CLOSED);
-
do {
struct page *page;

diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
index 4a69515dea75..e043216b545f 100644
--- a/fs/erofs/zdata.h
+++ b/fs/erofs/zdata.h
@@ -62,8 +62,16 @@ struct z_erofs_pcluster {
/* A: lower limit of decompressed length and if full length or not */
unsigned int length;

- /* I: physical cluster size in pages */
- unsigned short pclusterpages;
+ /* I: page offset of inline compressed data */
+ unsigned short pageofs_in;
+
+ union {
+ /* I: physical cluster size in pages */
+ unsigned short pclusterpages;
+
+ /* I: tailpacking inline compressed size */
+ unsigned short tailpacking_size;
+ };

/* I: compression algorithm format */
unsigned char algorithmformat;
@@ -94,6 +102,18 @@ struct z_erofs_decompressqueue {
} u;
};

+static inline bool z_erofs_is_inline_pcluster(struct z_erofs_pcluster *pcl)
+{
+ return !pcl->obj.index;
+}
+
+static inline unsigned int z_erofs_pclusterpages(struct z_erofs_pcluster *pcl)
+{
+ if (z_erofs_is_inline_pcluster(pcl))
+ return 1;
+ return pcl->pclusterpages;
+}
+
#define Z_EROFS_ONLINEPAGE_COUNT_BITS 2
#define Z_EROFS_ONLINEPAGE_COUNT_MASK ((1 << Z_EROFS_ONLINEPAGE_COUNT_BITS) - 1)
#define Z_EROFS_ONLINEPAGE_INDEX_SHIFT (Z_EROFS_ONLINEPAGE_COUNT_BITS)
--
2.20.1
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