Commit 2349d2fa authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: sunset unneeded NOFAILs 



With iterative development, our codebase can now deal with compressed
buffer misses properly if both in-place I/O and compressed buffer
allocation fail.

Note that if readahead fails (with non-uptodate folios), the original
request will then fall back to synchronous read, and `.read_folio()`
should return appropriate errnos; otherwise -EIO will be passed to
user space, which is unexpected.

To simplify rarely encountered failure paths, a mimic decompression
will be just used.  Before that, failure reasons are recorded in
compressed_bvecs[] and they also act as placeholders to avoid in-place
pages.  They will be parsed just before decompression and then pass
back to `.read_folio()`.

Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240905084732.2684515-1-hsiangkao@linux.alibaba.com
parent 8bdb6a83

fs/erofs/zdata.c

+31 −26
Original line number Diff line number Diff line
@@ -1154,9 +1154,10 @@ static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be, 
		struct z_erofs_bvec *bvec = &pcl->compressed_bvecs[i];

		struct page *page = bvec->page;



		/* compressed data ought to be valid before decompressing */

		if (!page) {

			err = -EIO;

		/* compressed data ought to be valid when decompressing */

		if (IS_ERR(page) || !page) {

			bvec->page = NULL;	/* clear the failure reason */

			err = page ? PTR_ERR(page) : -EIO;

			continue;

		}

		be->compressed_pages[i] = page;
@@ -1232,8 +1233,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, 
					.inplace_io = overlapped,

					.partial_decoding = pcl->partial,

					.fillgaps = pcl->multibases,

					.gfp = pcl->besteffort ?

						GFP_KERNEL | __GFP_NOFAIL :

					.gfp = pcl->besteffort ? GFP_KERNEL :

						GFP_NOWAIT | __GFP_NORETRY

				 }, be->pagepool);
@@ -1297,7 +1297,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, 
	return err;

}



static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,

static int z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,

				    struct page **pagepool)

{

	struct z_erofs_decompress_backend be = {
@@ -1307,6 +1307,7 @@ static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io, 
			LIST_HEAD_INIT(be.decompressed_secondary_bvecs),

	};

	z_erofs_next_pcluster_t owned = io->head;

	int err = io->eio ? -EIO : 0;



	while (owned != Z_EROFS_PCLUSTER_TAIL) {

		DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
@@ -1314,12 +1315,13 @@ static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io, 
		be.pcl = container_of(owned, struct z_erofs_pcluster, next);

		owned = READ_ONCE(be.pcl->next);



		z_erofs_decompress_pcluster(&be, io->eio ? -EIO : 0);

		err = z_erofs_decompress_pcluster(&be, err) ?: err;

		if (z_erofs_is_inline_pcluster(be.pcl))

			z_erofs_free_pcluster(be.pcl);

		else

			erofs_workgroup_put(&be.pcl->obj);

	}

	return err;

}



static void z_erofs_decompressqueue_work(struct work_struct *work)
@@ -1462,17 +1464,21 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, 
	folio_unlock(folio);

	folio_put(folio);

out_allocfolio:

	page = erofs_allocpage(&f->pagepool, gfp | __GFP_NOFAIL);

	page = erofs_allocpage(&f->pagepool, gfp);

	spin_lock(&pcl->obj.lockref.lock);

	if (unlikely(pcl->compressed_bvecs[nr].page != zbv.page)) {

		if (page)

			erofs_pagepool_add(&f->pagepool, page);

		spin_unlock(&pcl->obj.lockref.lock);

		cond_resched();

		goto repeat;

	}

	bvec->bv_page = pcl->compressed_bvecs[nr].page = page;

	folio = page_folio(page);

	pcl->compressed_bvecs[nr].page = page ? page : ERR_PTR(-ENOMEM);

	spin_unlock(&pcl->obj.lockref.lock);

	bvec->bv_page = page;

	if (!page)

		return;

	folio = page_folio(page);

out_tocache:

	if (!tocache || bs != PAGE_SIZE ||

	    filemap_add_folio(mc, folio, pcl->obj.index + nr, gfp)) {
@@ -1698,26 +1704,28 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, 
	z_erofs_decompress_kickoff(q[JQ_SUBMIT], nr_bios);

}



static void z_erofs_runqueue(struct z_erofs_decompress_frontend *f,

			     bool force_fg, bool ra)

static int z_erofs_runqueue(struct z_erofs_decompress_frontend *f,

			    unsigned int ra_folios)

{

	struct z_erofs_decompressqueue io[NR_JOBQUEUES];

	struct erofs_sb_info *sbi = EROFS_I_SB(f->inode);

	bool force_fg = z_erofs_is_sync_decompress(sbi, ra_folios);

	int err;



	if (f->owned_head == Z_EROFS_PCLUSTER_TAIL)

		return;

	z_erofs_submit_queue(f, io, &force_fg, ra);

		return 0;

	z_erofs_submit_queue(f, io, &force_fg, !!ra_folios);



	/* handle bypass queue (no i/o pclusters) immediately */

	z_erofs_decompress_queue(&io[JQ_BYPASS], &f->pagepool);



	err = z_erofs_decompress_queue(&io[JQ_BYPASS], &f->pagepool);

	if (!force_fg)

		return;

		return err;



	/* wait until all bios are completed */

	wait_for_completion_io(&io[JQ_SUBMIT].u.done);



	/* handle synchronous decompress queue in the caller context */

	z_erofs_decompress_queue(&io[JQ_SUBMIT], &f->pagepool);

	return z_erofs_decompress_queue(&io[JQ_SUBMIT], &f->pagepool) ?: err;

}



/*
@@ -1779,7 +1787,6 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f, 
static int z_erofs_read_folio(struct file *file, struct folio *folio)

{

	struct inode *const inode = folio->mapping->host;

	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);

	struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);

	int err;
@@ -1791,9 +1798,8 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio) 
	z_erofs_pcluster_readmore(&f, NULL, false);

	z_erofs_pcluster_end(&f);



	/* if some compressed cluster ready, need submit them anyway */

	z_erofs_runqueue(&f, z_erofs_is_sync_decompress(sbi, 0), false);



	/* if some pclusters are ready, need submit them anyway */

	err = z_erofs_runqueue(&f, 0) ?: err;

	if (err && err != -EINTR)

		erofs_err(inode->i_sb, "read error %d @ %lu of nid %llu",

			  err, folio->index, EROFS_I(inode)->nid);
@@ -1806,7 +1812,6 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio) 
static void z_erofs_readahead(struct readahead_control *rac)

{

	struct inode *const inode = rac->mapping->host;

	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);

	struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);

	struct folio *head = NULL, *folio;

	unsigned int nr_folios;
@@ -1836,7 +1841,7 @@ static void z_erofs_readahead(struct readahead_control *rac) 
	z_erofs_pcluster_readmore(&f, rac, false);

	z_erofs_pcluster_end(&f);



	z_erofs_runqueue(&f, z_erofs_is_sync_decompress(sbi, nr_folios), true);

	(void)z_erofs_runqueue(&f, nr_folios);

	erofs_put_metabuf(&f.map.buf);

	erofs_release_pages(&f.pagepool);

}