[PATCH 1/5] erofs: support I/O submission for sub-page compressed blocks
Gao Xiang
hsiangkao at linux.alibaba.com
Wed Dec 6 20:10:53 AEDT 2023
Add a basic I/O submission path first to support sub-page blocks:
- Temporary short-lived pages will be used entirely;
- In-place I/O pages can be used partially, but compressed pages need
to be able to be mapped in contiguous virtual memory.
As a start, currently cache decompression is explicitly disabled for
sub-page blocks, which will be supported in the future.
Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
---
fs/erofs/zdata.c | 156 ++++++++++++++++++++++-------------------------
1 file changed, 74 insertions(+), 82 deletions(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index a33cd6757f98..421c0a88a0ca 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1435,86 +1435,85 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
z_erofs_decompressqueue_work(&io->u.work);
}
-static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
- unsigned int nr,
- struct page **pagepool,
- struct address_space *mc)
+static void z_erofs_fill_bio_vec(struct bio_vec *bvec,
+ struct z_erofs_decompress_frontend *f,
+ struct z_erofs_pcluster *pcl,
+ unsigned int nr,
+ struct address_space *mc)
{
- const pgoff_t index = pcl->obj.index;
gfp_t gfp = mapping_gfp_mask(mc);
bool tocache = false;
-
+ struct z_erofs_bvec *zbv = pcl->compressed_bvecs + nr;
struct address_space *mapping;
- struct page *oldpage, *page;
- int justfound;
+ struct page *page, *oldpage;
+ int justfound, bs = i_blocksize(f->inode);
+ /* Except for inplace pages, the entire page can be used for I/Os */
+ bvec->bv_offset = 0;
+ bvec->bv_len = PAGE_SIZE;
repeat:
- page = READ_ONCE(pcl->compressed_bvecs[nr].page);
- oldpage = page;
-
- if (!page)
+ oldpage = READ_ONCE(zbv->page);
+ if (!oldpage)
goto out_allocpage;
- justfound = (unsigned long)page & 1UL;
- page = (struct page *)((unsigned long)page & ~1UL);
+ justfound = (unsigned long)oldpage & 1UL;
+ page = (struct page *)((unsigned long)oldpage & ~1UL);
+ bvec->bv_page = page;
+ DBG_BUGON(z_erofs_is_shortlived_page(page));
/*
- * preallocated cached pages, which is used to avoid direct reclaim
- * otherwise, it will go inplace I/O path instead.
+ * Handle preallocated cached pages. We tried to allocate such pages
+ * without triggering direct reclaim. If allocation failed, inplace
+ * file-backed pages will be used instead.
*/
if (page->private == Z_EROFS_PREALLOCATED_PAGE) {
- WRITE_ONCE(pcl->compressed_bvecs[nr].page, page);
set_page_private(page, 0);
+ WRITE_ONCE(zbv->page, page);
tocache = true;
goto out_tocache;
}
- mapping = READ_ONCE(page->mapping);
+ mapping = READ_ONCE(page->mapping);
/*
- * file-backed online pages in plcuster are all locked steady,
- * therefore it is impossible for `mapping' to be NULL.
+ * File-backed pages for inplace I/Os are all locked steady,
+ * therefore it is impossible for `mapping` to be NULL.
*/
- if (mapping && mapping != mc)
- /* ought to be unmanaged pages */
- goto out;
-
- /* directly return for shortlived page as well */
- if (z_erofs_is_shortlived_page(page))
- goto out;
+ if (mapping && mapping != mc) {
+ if (zbv->offset < 0)
+ bvec->bv_offset = round_up(-zbv->offset, bs);
+ bvec->bv_len = round_up(zbv->end, bs) - bvec->bv_offset;
+ return;
+ }
lock_page(page);
-
/* only true if page reclaim goes wrong, should never happen */
DBG_BUGON(justfound && PagePrivate(page));
- /* the page is still in manage cache */
+ /* the cached page is still in managed cache */
if (page->mapping == mc) {
- WRITE_ONCE(pcl->compressed_bvecs[nr].page, page);
-
+ WRITE_ONCE(zbv->page, page);
+ /*
+ * The cached page is still available but without a valid
+ * `->private` pcluster hint. Let's reconnect them.
+ */
if (!PagePrivate(page)) {
- /*
- * impossible to be !PagePrivate(page) for
- * the current restriction as well if
- * the page is already in compressed_bvecs[].
- */
DBG_BUGON(!justfound);
-
- justfound = 0;
- set_page_private(page, (unsigned long)pcl);
- SetPagePrivate(page);
+ /* compressed_bvecs[] already takes a ref */
+ attach_page_private(page, pcl);
+ put_page(page);
}
- /* no need to submit io if it is already up-to-date */
+ /* no need to submit if it is already up-to-date */
if (PageUptodate(page)) {
unlock_page(page);
- page = NULL;
+ bvec->bv_page = NULL;
}
- goto out;
+ return;
}
/*
- * the managed page has been truncated, it's unsafe to
- * reuse this one, let's allocate a new cache-managed page.
+ * It has been truncated, so it's unsafe to reuse this one. Let's
+ * allocate a new page for compressed data.
*/
DBG_BUGON(page->mapping);
DBG_BUGON(!justfound);
@@ -1523,25 +1522,23 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
unlock_page(page);
put_page(page);
out_allocpage:
- page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
- if (oldpage != cmpxchg(&pcl->compressed_bvecs[nr].page,
- oldpage, page)) {
- erofs_pagepool_add(pagepool, page);
+ page = erofs_allocpage(&f->pagepool, gfp | __GFP_NOFAIL);
+ if (oldpage != cmpxchg(&zbv->page, oldpage, page)) {
+ erofs_pagepool_add(&f->pagepool, page);
cond_resched();
goto repeat;
}
+ bvec->bv_page = page;
out_tocache:
- if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
- /* turn into temporary page if fails (1 ref) */
+ if (!tocache || bs != PAGE_SIZE ||
+ add_to_page_cache_lru(page, mc, pcl->obj.index + nr, gfp)) {
+ /* turn into a temporary shortlived page (1 ref) */
set_page_private(page, Z_EROFS_SHORTLIVED_PAGE);
- goto out;
+ return;
}
attach_page_private(page, pcl);
- /* drop a refcount added by allocpage (then we have 2 refs here) */
+ /* drop a refcount added by allocpage (then 2 refs in total here) */
put_page(page);
-
-out: /* the only exit (for tracing and debugging) */
- return page;
}
static struct z_erofs_decompressqueue *jobqueue_init(struct super_block *sb,
@@ -1596,7 +1593,7 @@ static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
qtail[JQ_BYPASS] = &pcl->next;
}
-static void z_erofs_decompressqueue_endio(struct bio *bio)
+static void z_erofs_submissionqueue_endio(struct bio *bio)
{
struct z_erofs_decompressqueue *q = bio->bi_private;
blk_status_t err = bio->bi_status;
@@ -1608,7 +1605,6 @@ static void z_erofs_decompressqueue_endio(struct bio *bio)
DBG_BUGON(PageUptodate(page));
DBG_BUGON(z_erofs_page_is_invalidated(page));
-
if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
if (!err)
SetPageUptodate(page);
@@ -1631,17 +1627,14 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
z_erofs_next_pcluster_t owned_head = f->owned_head;
/* bio is NULL initially, so no need to initialize last_{index,bdev} */
- pgoff_t last_index;
+ erofs_off_t last_pa;
struct block_device *last_bdev;
unsigned int nr_bios = 0;
struct bio *bio = NULL;
unsigned long pflags;
int memstall = 0;
- /*
- * if managed cache is enabled, bypass jobqueue is needed,
- * no need to read from device for all pclusters in this queue.
- */
+ /* No need to read from device for pclusters in the bypass queue. */
q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, force_fg);
@@ -1654,7 +1647,8 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
do {
struct erofs_map_dev mdev;
struct z_erofs_pcluster *pcl;
- pgoff_t cur, end;
+ erofs_off_t cur, end;
+ struct bio_vec bvec;
unsigned int i = 0;
bool bypass = true;
@@ -1673,18 +1667,14 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
};
(void)erofs_map_dev(sb, &mdev);
- cur = erofs_blknr(sb, mdev.m_pa);
- end = cur + pcl->pclusterpages;
-
+ cur = mdev.m_pa;
+ end = cur + pcl->pclusterpages << PAGE_SHIFT;
do {
- struct page *page;
-
- page = pickup_page_for_submission(pcl, i++,
- &f->pagepool, mc);
- if (!page)
+ z_erofs_fill_bio_vec(&bvec, f, pcl, i++, mc);
+ if (!bvec.bv_page)
continue;
- if (bio && (cur != last_index + 1 ||
+ if (bio && (cur != last_pa ||
last_bdev != mdev.m_bdev)) {
submit_bio_retry:
submit_bio(bio);
@@ -1695,7 +1685,8 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
bio = NULL;
}
- if (unlikely(PageWorkingset(page)) && !memstall) {
+ if (unlikely(PageWorkingset(bvec.bv_page)) &&
+ !memstall) {
psi_memstall_enter(&pflags);
memstall = 1;
}
@@ -1703,23 +1694,24 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
if (!bio) {
bio = bio_alloc(mdev.m_bdev, BIO_MAX_VECS,
REQ_OP_READ, GFP_NOIO);
- bio->bi_end_io = z_erofs_decompressqueue_endio;
-
- last_bdev = mdev.m_bdev;
- bio->bi_iter.bi_sector = (sector_t)cur <<
- (sb->s_blocksize_bits - 9);
+ bio->bi_end_io = z_erofs_submissionqueue_endio;
+ bio->bi_iter.bi_sector = cur >> 9;
bio->bi_private = q[JQ_SUBMIT];
if (readahead)
bio->bi_opf |= REQ_RAHEAD;
++nr_bios;
+ last_bdev = mdev.m_bdev;
}
- if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
+ if (cur + bvec.bv_len > end)
+ bvec.bv_len = end - cur;
+ if (!bio_add_page(bio, bvec.bv_page, bvec.bv_len,
+ bvec.bv_offset))
goto submit_bio_retry;
- last_index = cur;
+ last_pa = cur + bvec.bv_len;
bypass = false;
- } while (++cur < end);
+ } while ((cur += bvec.bv_len) < end);
if (!bypass)
qtail[JQ_SUBMIT] = &pcl->next;
--
2.39.3
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