* [PATCH v3] f2fs: clean up post-read processing
@ 2021-01-05 6:33 Eric Biggers
2021-01-05 7:12 ` [f2fs-dev] " Chao Yu
0 siblings, 1 reply; 2+ messages in thread
From: Eric Biggers @ 2021-01-05 6:33 UTC (permalink / raw)
To: linux-f2fs-devel; +Cc: linux-fscrypt
From: Eric Biggers <ebiggers@google.com>
Rework the post-read processing logic to be much easier to understand.
At least one bug is fixed by this: if an I/O error occurred when reading
from disk, decryption and verity would be performed on the uninitialized
data, causing misleading messages in the kernel log.
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
Changed v2 => v3:
- Moved STEP_DECOMPRESS handling into its own function.
- Renamed f2fs_put_page_decompress_io_ctx() to f2fs_put_page_dic().
- Kept old tracepoint name.
- Improved some comments.
Changed v1 => v2:
- Rebased onto v5.11-rc1.
fs/f2fs/compress.c | 149 +++++++++++++------
fs/f2fs/data.c | 357 ++++++++++++++++++---------------------------
fs/f2fs/f2fs.h | 55 ++++++-
3 files changed, 297 insertions(+), 264 deletions(-)
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 4bcbacfe33259..68dc8b59d16a9 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -721,38 +721,27 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
return ret;
}
-void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
+static void f2fs_decompress_cluster(struct decompress_io_ctx *dic)
{
- struct decompress_io_ctx *dic =
- (struct decompress_io_ctx *)page_private(page);
struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
- struct f2fs_inode_info *fi= F2FS_I(dic->inode);
+ struct f2fs_inode_info *fi = F2FS_I(dic->inode);
const struct f2fs_compress_ops *cops =
f2fs_cops[fi->i_compress_algorithm];
int ret;
int i;
- dec_page_count(sbi, F2FS_RD_DATA);
-
- if (bio->bi_status || PageError(page))
- dic->failed = true;
-
- if (atomic_dec_return(&dic->pending_pages))
- return;
-
trace_f2fs_decompress_pages_start(dic->inode, dic->cluster_idx,
dic->cluster_size, fi->i_compress_algorithm);
- /* submit partial compressed pages */
if (dic->failed) {
ret = -EIO;
- goto out_free_dic;
+ goto out_end_io;
}
dic->tpages = page_array_alloc(dic->inode, dic->cluster_size);
if (!dic->tpages) {
ret = -ENOMEM;
- goto out_free_dic;
+ goto out_end_io;
}
for (i = 0; i < dic->cluster_size; i++) {
@@ -764,20 +753,20 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
dic->tpages[i] = f2fs_compress_alloc_page();
if (!dic->tpages[i]) {
ret = -ENOMEM;
- goto out_free_dic;
+ goto out_end_io;
}
}
if (cops->init_decompress_ctx) {
ret = cops->init_decompress_ctx(dic);
if (ret)
- goto out_free_dic;
+ goto out_end_io;
}
dic->rbuf = f2fs_vmap(dic->tpages, dic->cluster_size);
if (!dic->rbuf) {
ret = -ENOMEM;
- goto destroy_decompress_ctx;
+ goto out_destroy_decompress_ctx;
}
dic->cbuf = f2fs_vmap(dic->cpages, dic->nr_cpages);
@@ -816,18 +805,34 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
vm_unmap_ram(dic->cbuf, dic->nr_cpages);
out_vunmap_rbuf:
vm_unmap_ram(dic->rbuf, dic->cluster_size);
-destroy_decompress_ctx:
+out_destroy_decompress_ctx:
if (cops->destroy_decompress_ctx)
cops->destroy_decompress_ctx(dic);
-out_free_dic:
- if (!verity)
- f2fs_decompress_end_io(dic->rpages, dic->cluster_size,
- ret, false);
-
+out_end_io:
trace_f2fs_decompress_pages_end(dic->inode, dic->cluster_idx,
dic->clen, ret);
- if (!verity)
- f2fs_free_dic(dic);
+ f2fs_decompress_end_io(dic, ret);
+}
+
+/*
+ * This is called when a page of a compressed cluster has been read from disk
+ * (or failed to be read from disk). It checks whether this page was the last
+ * page being waited on in the cluster, and if so, it decompresses the cluster
+ * (or in the case of a failure, cleans up without actually decompressing).
+ */
+void f2fs_end_read_compressed_page(struct page *page, bool failed)
+{
+ struct decompress_io_ctx *dic =
+ (struct decompress_io_ctx *)page_private(page);
+ struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
+
+ dec_page_count(sbi, F2FS_RD_DATA);
+
+ if (failed)
+ WRITE_ONCE(dic->failed, true);
+
+ if (atomic_dec_and_test(&dic->remaining_pages))
+ f2fs_decompress_cluster(dic);
}
static bool is_page_in_cluster(struct compress_ctx *cc, pgoff_t index)
@@ -1494,6 +1499,8 @@ int f2fs_write_multi_pages(struct compress_ctx *cc,
return err;
}
+static void f2fs_free_dic(struct decompress_io_ctx *dic);
+
struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc)
{
struct decompress_io_ctx *dic;
@@ -1512,12 +1519,14 @@ struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc)
dic->magic = F2FS_COMPRESSED_PAGE_MAGIC;
dic->inode = cc->inode;
- atomic_set(&dic->pending_pages, cc->nr_cpages);
+ atomic_set(&dic->remaining_pages, cc->nr_cpages);
dic->cluster_idx = cc->cluster_idx;
dic->cluster_size = cc->cluster_size;
dic->log_cluster_size = cc->log_cluster_size;
dic->nr_cpages = cc->nr_cpages;
+ refcount_set(&dic->refcnt, 1);
dic->failed = false;
+ dic->need_verity = f2fs_need_verity(cc->inode, start_idx);
for (i = 0; i < dic->cluster_size; i++)
dic->rpages[i] = cc->rpages[i];
@@ -1546,7 +1555,7 @@ struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc)
return ERR_PTR(-ENOMEM);
}
-void f2fs_free_dic(struct decompress_io_ctx *dic)
+static void f2fs_free_dic(struct decompress_io_ctx *dic)
{
int i;
@@ -1574,30 +1583,88 @@ void f2fs_free_dic(struct decompress_io_ctx *dic)
kmem_cache_free(dic_entry_slab, dic);
}
-void f2fs_decompress_end_io(struct page **rpages,
- unsigned int cluster_size, bool err, bool verity)
+static void f2fs_put_dic(struct decompress_io_ctx *dic)
+{
+ if (refcount_dec_and_test(&dic->refcnt))
+ f2fs_free_dic(dic);
+}
+
+/*
+ * Update and unlock the cluster's pagecache pages, and release the reference to
+ * the decompress_io_ctx that was being held for I/O completion.
+ */
+static void __f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed)
{
int i;
- for (i = 0; i < cluster_size; i++) {
- struct page *rpage = rpages[i];
+ for (i = 0; i < dic->cluster_size; i++) {
+ struct page *rpage = dic->rpages[i];
if (!rpage)
continue;
- if (err || PageError(rpage))
- goto clear_uptodate;
-
- if (!verity || fsverity_verify_page(rpage)) {
+ /* PG_error was set if verity failed. */
+ if (failed || PageError(rpage)) {
+ ClearPageUptodate(rpage);
+ /* will re-read again later */
+ ClearPageError(rpage);
+ } else {
SetPageUptodate(rpage);
- goto unlock;
}
-clear_uptodate:
- ClearPageUptodate(rpage);
- ClearPageError(rpage);
-unlock:
unlock_page(rpage);
}
+
+ f2fs_put_dic(dic);
+}
+
+static void f2fs_verify_cluster(struct work_struct *work)
+{
+ struct decompress_io_ctx *dic =
+ container_of(work, struct decompress_io_ctx, verity_work);
+ int i;
+
+ /* Verify the cluster's decompressed pages with fs-verity. */
+ for (i = 0; i < dic->cluster_size; i++) {
+ struct page *rpage = dic->rpages[i];
+
+ if (rpage && !fsverity_verify_page(rpage))
+ SetPageError(rpage);
+ }
+
+ __f2fs_decompress_end_io(dic, false);
+}
+
+/*
+ * This is called when a compressed cluster has been decompressed
+ * (or failed to be read and/or decompressed).
+ */
+void f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed)
+{
+ if (!failed && dic->need_verity) {
+ /*
+ * Note that to avoid deadlocks, the verity work can't be done
+ * on the decompression workqueue. This is because verifying
+ * the data pages can involve reading metadata pages from the
+ * file, and these metadata pages may be compressed.
+ */
+ INIT_WORK(&dic->verity_work, f2fs_verify_cluster);
+ fsverity_enqueue_verify_work(&dic->verity_work);
+ } else {
+ __f2fs_decompress_end_io(dic, failed);
+ }
+}
+
+/*
+ * Put a reference to a compressed page's decompress_io_ctx.
+ *
+ * This is called when the page is no longer needed and can be freed.
+ */
+void f2fs_put_page_dic(struct page *page)
+{
+ struct decompress_io_ctx *dic =
+ (struct decompress_io_ctx *)page_private(page);
+
+ f2fs_put_dic(dic);
}
int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index aa34d620bec98..720632fb72008 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -115,10 +115,21 @@ static enum count_type __read_io_type(struct page *page)
/* postprocessing steps for read bios */
enum bio_post_read_step {
- STEP_DECRYPT,
- STEP_DECOMPRESS_NOWQ, /* handle normal cluster data inplace */
- STEP_DECOMPRESS, /* handle compressed cluster data in workqueue */
- STEP_VERITY,
+#ifdef CONFIG_FS_ENCRYPTION
+ STEP_DECRYPT = 1 << 0,
+#else
+ STEP_DECRYPT = 0, /* compile out the decryption-related code */
+#endif
+#ifdef CONFIG_F2FS_FS_COMPRESSION
+ STEP_DECOMPRESS = 1 << 1,
+#else
+ STEP_DECOMPRESS = 0, /* compile out the decompression-related code */
+#endif
+#ifdef CONFIG_FS_VERITY
+ STEP_VERITY = 1 << 2,
+#else
+ STEP_VERITY = 0, /* compile out the verity-related code */
+#endif
};
struct bio_post_read_ctx {
@@ -128,25 +139,26 @@ struct bio_post_read_ctx {
unsigned int enabled_steps;
};
-static void __read_end_io(struct bio *bio, bool compr, bool verity)
+static void f2fs_finish_read_bio(struct bio *bio)
{
- struct page *page;
struct bio_vec *bv;
struct bvec_iter_all iter_all;
+ /*
+ * Update and unlock the bio's pagecache pages, and put the
+ * decompression context for any compressed pages.
+ */
bio_for_each_segment_all(bv, bio, iter_all) {
- page = bv->bv_page;
+ struct page *page = bv->bv_page;
-#ifdef CONFIG_F2FS_FS_COMPRESSION
- if (compr && f2fs_is_compressed_page(page)) {
- f2fs_decompress_pages(bio, page, verity);
+ if (f2fs_is_compressed_page(page)) {
+ if (bio->bi_status)
+ f2fs_end_read_compressed_page(page, true);
+ f2fs_put_page_dic(page);
continue;
}
- if (verity)
- continue;
-#endif
- /* PG_error was set if any post_read step failed */
+ /* PG_error was set if decryption or verity failed. */
if (bio->bi_status || PageError(page)) {
ClearPageUptodate(page);
/* will re-read again later */
@@ -157,181 +169,141 @@ static void __read_end_io(struct bio *bio, bool compr, bool verity)
dec_page_count(F2FS_P_SB(page), __read_io_type(page));
unlock_page(page);
}
-}
-
-static void f2fs_release_read_bio(struct bio *bio);
-static void __f2fs_read_end_io(struct bio *bio, bool compr, bool verity)
-{
- if (!compr)
- __read_end_io(bio, false, verity);
- f2fs_release_read_bio(bio);
-}
-
-static void f2fs_decompress_bio(struct bio *bio, bool verity)
-{
- __read_end_io(bio, true, verity);
-}
-
-static void bio_post_read_processing(struct bio_post_read_ctx *ctx);
-
-static void f2fs_decrypt_work(struct bio_post_read_ctx *ctx)
-{
- fscrypt_decrypt_bio(ctx->bio);
-}
-
-static void f2fs_decompress_work(struct bio_post_read_ctx *ctx)
-{
- f2fs_decompress_bio(ctx->bio, ctx->enabled_steps & (1 << STEP_VERITY));
-}
-
-#ifdef CONFIG_F2FS_FS_COMPRESSION
-static void f2fs_verify_pages(struct page **rpages, unsigned int cluster_size)
-{
- f2fs_decompress_end_io(rpages, cluster_size, false, true);
-}
-
-static void f2fs_verify_bio(struct bio *bio)
-{
- struct bio_vec *bv;
- struct bvec_iter_all iter_all;
-
- bio_for_each_segment_all(bv, bio, iter_all) {
- struct page *page = bv->bv_page;
- struct decompress_io_ctx *dic;
-
- dic = (struct decompress_io_ctx *)page_private(page);
-
- if (dic) {
- if (atomic_dec_return(&dic->verity_pages))
- continue;
- f2fs_verify_pages(dic->rpages,
- dic->cluster_size);
- f2fs_free_dic(dic);
- continue;
- }
-
- if (bio->bi_status || PageError(page))
- goto clear_uptodate;
- if (fsverity_verify_page(page)) {
- SetPageUptodate(page);
- goto unlock;
- }
-clear_uptodate:
- ClearPageUptodate(page);
- ClearPageError(page);
-unlock:
- dec_page_count(F2FS_P_SB(page), __read_io_type(page));
- unlock_page(page);
- }
+ if (bio->bi_private)
+ mempool_free(bio->bi_private, bio_post_read_ctx_pool);
+ bio_put(bio);
}
-#endif
-static void f2fs_verity_work(struct work_struct *work)
+static void f2fs_verify_bio(struct work_struct *work)
{
struct bio_post_read_ctx *ctx =
container_of(work, struct bio_post_read_ctx, work);
struct bio *bio = ctx->bio;
-#ifdef CONFIG_F2FS_FS_COMPRESSION
- unsigned int enabled_steps = ctx->enabled_steps;
-#endif
+ bool may_have_compressed_pages = (ctx->enabled_steps & STEP_DECOMPRESS);
/*
* fsverity_verify_bio() may call readpages() again, and while verity
- * will be disabled for this, decryption may still be needed, resulting
- * in another bio_post_read_ctx being allocated. So to prevent
- * deadlocks we need to release the current ctx to the mempool first.
- * This assumes that verity is the last post-read step.
+ * will be disabled for this, decryption and/or decompression may still
+ * be needed, resulting in another bio_post_read_ctx being allocated.
+ * So to prevent deadlocks we need to release the current ctx to the
+ * mempool first. This assumes that verity is the last post-read step.
*/
mempool_free(ctx, bio_post_read_ctx_pool);
bio->bi_private = NULL;
-#ifdef CONFIG_F2FS_FS_COMPRESSION
- /* previous step is decompression */
- if (enabled_steps & (1 << STEP_DECOMPRESS)) {
- f2fs_verify_bio(bio);
- f2fs_release_read_bio(bio);
- return;
+ /*
+ * Verify the bio's pages with fs-verity. Exclude compressed pages,
+ * as those were handled separately by f2fs_end_read_compressed_page().
+ */
+ if (may_have_compressed_pages) {
+ struct bio_vec *bv;
+ struct bvec_iter_all iter_all;
+
+ bio_for_each_segment_all(bv, bio, iter_all) {
+ struct page *page = bv->bv_page;
+
+ if (!f2fs_is_compressed_page(page) &&
+ !PageError(page) && !fsverity_verify_page(page))
+ SetPageError(page);
+ }
+ } else {
+ fsverity_verify_bio(bio);
}
-#endif
- fsverity_verify_bio(bio);
- __f2fs_read_end_io(bio, false, false);
+ f2fs_finish_read_bio(bio);
}
-static void f2fs_post_read_work(struct work_struct *work)
+/*
+ * If the bio's data needs to be verified with fs-verity, then enqueue the
+ * verity work for the bio. Otherwise finish the bio now.
+ *
+ * Note that to avoid deadlocks, the verity work can't be done on the
+ * decryption/decompression workqueue. This is because verifying the data pages
+ * can involve reading verity metadata pages from the file, and these verity
+ * metadata pages may be encrypted and/or compressed.
+ */
+static void f2fs_verify_and_finish_bio(struct bio *bio)
{
- struct bio_post_read_ctx *ctx =
- container_of(work, struct bio_post_read_ctx, work);
-
- if (ctx->enabled_steps & (1 << STEP_DECRYPT))
- f2fs_decrypt_work(ctx);
+ struct bio_post_read_ctx *ctx = bio->bi_private;
- if (ctx->enabled_steps & (1 << STEP_DECOMPRESS))
- f2fs_decompress_work(ctx);
-
- if (ctx->enabled_steps & (1 << STEP_VERITY)) {
- INIT_WORK(&ctx->work, f2fs_verity_work);
+ if (ctx && (ctx->enabled_steps & STEP_VERITY)) {
+ INIT_WORK(&ctx->work, f2fs_verify_bio);
fsverity_enqueue_verify_work(&ctx->work);
- return;
+ } else {
+ f2fs_finish_read_bio(bio);
}
-
- __f2fs_read_end_io(ctx->bio,
- ctx->enabled_steps & (1 << STEP_DECOMPRESS), false);
}
-static void f2fs_enqueue_post_read_work(struct f2fs_sb_info *sbi,
- struct work_struct *work)
-{
- queue_work(sbi->post_read_wq, work);
-}
-
-static void bio_post_read_processing(struct bio_post_read_ctx *ctx)
+/*
+ * Handle STEP_DECOMPRESS by decompressing any compressed clusters whose last
+ * remaining page was read by @ctx->bio.
+ *
+ * Note that a bio may span clusters (even a mix of compressed and uncompressed
+ * clusters) or be for just part of a cluster. STEP_DECOMPRESS just indicates
+ * that the bio includes at least one compressed page. The actual decompression
+ * is done on a per-cluster basis, not a per-bio basis.
+ */
+static void f2fs_handle_step_decompress(struct bio_post_read_ctx *ctx)
{
- /*
- * We use different work queues for decryption and for verity because
- * verity may require reading metadata pages that need decryption, and
- * we shouldn't recurse to the same workqueue.
- */
+ struct bio_vec *bv;
+ struct bvec_iter_all iter_all;
+ bool all_compressed = true;
- if (ctx->enabled_steps & (1 << STEP_DECRYPT) ||
- ctx->enabled_steps & (1 << STEP_DECOMPRESS)) {
- INIT_WORK(&ctx->work, f2fs_post_read_work);
- f2fs_enqueue_post_read_work(ctx->sbi, &ctx->work);
- return;
- }
+ bio_for_each_segment_all(bv, ctx->bio, iter_all) {
+ struct page *page = bv->bv_page;
- if (ctx->enabled_steps & (1 << STEP_VERITY)) {
- INIT_WORK(&ctx->work, f2fs_verity_work);
- fsverity_enqueue_verify_work(&ctx->work);
- return;
+ /* PG_error was set if decryption failed. */
+ if (f2fs_is_compressed_page(page))
+ f2fs_end_read_compressed_page(page, PageError(page));
+ else
+ all_compressed = false;
}
- __f2fs_read_end_io(ctx->bio, false, false);
+ /*
+ * Optimization: if all the bio's pages are compressed, then scheduling
+ * the per-bio verity work is unnecessary, as verity will be fully
+ * handled at the compression cluster level.
+ */
+ if (all_compressed)
+ ctx->enabled_steps &= ~STEP_VERITY;
}
-static bool f2fs_bio_post_read_required(struct bio *bio)
+static void f2fs_post_read_work(struct work_struct *work)
{
- return bio->bi_private;
+ struct bio_post_read_ctx *ctx =
+ container_of(work, struct bio_post_read_ctx, work);
+
+ if (ctx->enabled_steps & STEP_DECRYPT)
+ fscrypt_decrypt_bio(ctx->bio);
+
+ if (ctx->enabled_steps & STEP_DECOMPRESS)
+ f2fs_handle_step_decompress(ctx);
+
+ f2fs_verify_and_finish_bio(ctx->bio);
}
static void f2fs_read_end_io(struct bio *bio)
{
struct f2fs_sb_info *sbi = F2FS_P_SB(bio_first_page_all(bio));
+ struct bio_post_read_ctx *ctx = bio->bi_private;
if (time_to_inject(sbi, FAULT_READ_IO)) {
f2fs_show_injection_info(sbi, FAULT_READ_IO);
bio->bi_status = BLK_STS_IOERR;
}
- if (f2fs_bio_post_read_required(bio)) {
- struct bio_post_read_ctx *ctx = bio->bi_private;
-
- bio_post_read_processing(ctx);
+ if (bio->bi_status) {
+ f2fs_finish_read_bio(bio);
return;
}
- __f2fs_read_end_io(bio, false, false);
+ if (ctx && (ctx->enabled_steps & (STEP_DECRYPT | STEP_DECOMPRESS))) {
+ INIT_WORK(&ctx->work, f2fs_post_read_work);
+ queue_work(ctx->sbi->post_read_wq, &ctx->work);
+ } else {
+ f2fs_verify_and_finish_bio(bio);
+ }
}
static void f2fs_write_end_io(struct bio *bio)
@@ -1022,16 +994,9 @@ void f2fs_submit_page_write(struct f2fs_io_info *fio)
up_write(&io->io_rwsem);
}
-static inline bool f2fs_need_verity(const struct inode *inode, pgoff_t idx)
-{
- return fsverity_active(inode) &&
- idx < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
-}
-
static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
unsigned nr_pages, unsigned op_flag,
- pgoff_t first_idx, bool for_write,
- bool for_verity)
+ pgoff_t first_idx, bool for_write)
{
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
struct bio *bio;
@@ -1050,13 +1015,19 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
bio_set_op_attrs(bio, REQ_OP_READ, op_flag);
if (fscrypt_inode_uses_fs_layer_crypto(inode))
- post_read_steps |= 1 << STEP_DECRYPT;
- if (f2fs_compressed_file(inode))
- post_read_steps |= 1 << STEP_DECOMPRESS_NOWQ;
- if (for_verity && f2fs_need_verity(inode, first_idx))
- post_read_steps |= 1 << STEP_VERITY;
+ post_read_steps |= STEP_DECRYPT;
+
+ if (f2fs_need_verity(inode, first_idx))
+ post_read_steps |= STEP_VERITY;
+
+ /*
+ * STEP_DECOMPRESS is handled specially, since a compressed file might
+ * contain both compressed and uncompressed clusters. We'll allocate a
+ * bio_post_read_ctx if the file is compressed, but the caller is
+ * responsible for enabling STEP_DECOMPRESS if it's actually needed.
+ */
- if (post_read_steps) {
+ if (post_read_steps || f2fs_compressed_file(inode)) {
/* Due to the mempool, this never fails. */
ctx = mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS);
ctx->bio = bio;
@@ -1068,13 +1039,6 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
return bio;
}
-static void f2fs_release_read_bio(struct bio *bio)
-{
- if (bio->bi_private)
- mempool_free(bio->bi_private, bio_post_read_ctx_pool);
- bio_put(bio);
-}
-
/* This can handle encryption stuffs */
static int f2fs_submit_page_read(struct inode *inode, struct page *page,
block_t blkaddr, int op_flags, bool for_write)
@@ -1083,7 +1047,7 @@ static int f2fs_submit_page_read(struct inode *inode, struct page *page,
struct bio *bio;
bio = f2fs_grab_read_bio(inode, blkaddr, 1, op_flags,
- page->index, for_write, true);
+ page->index, for_write);
if (IS_ERR(bio))
return PTR_ERR(bio);
@@ -2121,7 +2085,7 @@ static int f2fs_read_single_page(struct inode *inode, struct page *page,
if (bio == NULL) {
bio = f2fs_grab_read_bio(inode, block_nr, nr_pages,
is_readahead ? REQ_RAHEAD : 0, page->index,
- false, true);
+ false);
if (IS_ERR(bio)) {
ret = PTR_ERR(bio);
bio = NULL;
@@ -2167,8 +2131,6 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
sector_t last_block_in_file;
const unsigned blocksize = blks_to_bytes(inode, 1);
struct decompress_io_ctx *dic = NULL;
- struct bio_post_read_ctx *ctx;
- bool for_verity = false;
int i;
int ret = 0;
@@ -2234,29 +2196,10 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
goto out_put_dnode;
}
- /*
- * It's possible to enable fsverity on the fly when handling a cluster,
- * which requires complicated error handling. Instead of adding more
- * complexity, let's give a rule where end_io post-processes fsverity
- * per cluster. In order to do that, we need to submit bio, if previous
- * bio sets a different post-process policy.
- */
- if (fsverity_active(cc->inode)) {
- atomic_set(&dic->verity_pages, cc->nr_cpages);
- for_verity = true;
-
- if (bio) {
- ctx = bio->bi_private;
- if (!(ctx->enabled_steps & (1 << STEP_VERITY))) {
- __submit_bio(sbi, bio, DATA);
- bio = NULL;
- }
- }
- }
-
for (i = 0; i < dic->nr_cpages; i++) {
struct page *page = dic->cpages[i];
block_t blkaddr;
+ struct bio_post_read_ctx *ctx;
blkaddr = data_blkaddr(dn.inode, dn.node_page,
dn.ofs_in_node + i + 1);
@@ -2272,31 +2215,10 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
if (!bio) {
bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages,
is_readahead ? REQ_RAHEAD : 0,
- page->index, for_write, for_verity);
+ page->index, for_write);
if (IS_ERR(bio)) {
- unsigned int remained = dic->nr_cpages - i;
- bool release = false;
-
ret = PTR_ERR(bio);
- dic->failed = true;
-
- if (for_verity) {
- if (!atomic_sub_return(remained,
- &dic->verity_pages))
- release = true;
- } else {
- if (!atomic_sub_return(remained,
- &dic->pending_pages))
- release = true;
- }
-
- if (release) {
- f2fs_decompress_end_io(dic->rpages,
- cc->cluster_size, true,
- false);
- f2fs_free_dic(dic);
- }
-
+ f2fs_decompress_end_io(dic, ret);
f2fs_put_dnode(&dn);
*bio_ret = NULL;
return ret;
@@ -2308,10 +2230,9 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
if (bio_add_page(bio, page, blocksize, 0) < blocksize)
goto submit_and_realloc;
- /* tag STEP_DECOMPRESS to handle IO in wq */
ctx = bio->bi_private;
- if (!(ctx->enabled_steps & (1 << STEP_DECOMPRESS)))
- ctx->enabled_steps |= 1 << STEP_DECOMPRESS;
+ ctx->enabled_steps |= STEP_DECOMPRESS;
+ refcount_inc(&dic->refcnt);
inc_page_count(sbi, F2FS_RD_DATA);
f2fs_update_iostat(sbi, FS_DATA_READ_IO, F2FS_BLKSIZE);
@@ -2328,7 +2249,13 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
out_put_dnode:
f2fs_put_dnode(&dn);
out:
- f2fs_decompress_end_io(cc->rpages, cc->cluster_size, true, false);
+ for (i = 0; i < cc->cluster_size; i++) {
+ if (cc->rpages[i]) {
+ ClearPageUptodate(cc->rpages[i]);
+ ClearPageError(cc->rpages[i]);
+ unlock_page(cc->rpages[i]);
+ }
+ }
*bio_ret = bio;
return ret;
}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index bb11759191dcc..aebb139f9fa44 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1337,7 +1337,7 @@ struct compress_io_ctx {
atomic_t pending_pages; /* in-flight compressed page count */
};
-/* decompress io context for read IO path */
+/* Context for decompressing one cluster on the read IO path */
struct decompress_io_ctx {
u32 magic; /* magic number to indicate page is compressed */
struct inode *inode; /* inode the context belong to */
@@ -1353,11 +1353,37 @@ struct decompress_io_ctx {
struct compress_data *cbuf; /* virtual mapped address on cpages */
size_t rlen; /* valid data length in rbuf */
size_t clen; /* valid data length in cbuf */
- atomic_t pending_pages; /* in-flight compressed page count */
- atomic_t verity_pages; /* in-flight page count for verity */
- bool failed; /* indicate IO error during decompression */
+
+ /*
+ * The number of compressed pages remaining to be read in this cluster.
+ * This is initially nr_cpages. It is decremented by 1 each time a page
+ * has been read (or failed to be read). When it reaches 0, the cluster
+ * is decompressed (or an error is reported).
+ *
+ * If an error occurs before all the pages have been submitted for I/O,
+ * then this will never reach 0. In this case the I/O submitter is
+ * responsible for calling f2fs_decompress_end_io() instead.
+ */
+ atomic_t remaining_pages;
+
+ /*
+ * Number of references to this decompress_io_ctx.
+ *
+ * One reference is held for I/O completion. This reference is dropped
+ * after the pagecache pages are updated and unlocked -- either after
+ * decompression (and verity if enabled), or after an error.
+ *
+ * In addition, each compressed page holds a reference while it is in a
+ * bio. These references are necessary prevent compressed pages from
+ * being freed while they are still in a bio.
+ */
+ refcount_t refcnt;
+
+ bool failed; /* IO error occurred before decompression? */
+ bool need_verity; /* need fs-verity verification after decompression? */
void *private; /* payload buffer for specified decompression algorithm */
void *private2; /* extra payload buffer */
+ struct work_struct verity_work; /* work to verify the decompressed pages */
};
#define NULL_CLUSTER ((unsigned int)(~0))
@@ -3876,7 +3902,7 @@ void f2fs_compress_write_end_io(struct bio *bio, struct page *page);
bool f2fs_is_compress_backend_ready(struct inode *inode);
int f2fs_init_compress_mempool(void);
void f2fs_destroy_compress_mempool(void);
-void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity);
+void f2fs_end_read_compressed_page(struct page *page, bool failed);
bool f2fs_cluster_is_empty(struct compress_ctx *cc);
bool f2fs_cluster_can_merge_page(struct compress_ctx *cc, pgoff_t index);
void f2fs_compress_ctx_add_page(struct compress_ctx *cc, struct page *page);
@@ -3889,9 +3915,8 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
unsigned nr_pages, sector_t *last_block_in_bio,
bool is_readahead, bool for_write);
struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc);
-void f2fs_free_dic(struct decompress_io_ctx *dic);
-void f2fs_decompress_end_io(struct page **rpages,
- unsigned int cluster_size, bool err, bool verity);
+void f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed);
+void f2fs_put_page_dic(struct page *page);
int f2fs_init_compress_ctx(struct compress_ctx *cc);
void f2fs_destroy_compress_ctx(struct compress_ctx *cc);
void f2fs_init_compress_info(struct f2fs_sb_info *sbi);
@@ -3915,6 +3940,14 @@ static inline struct page *f2fs_compress_control_page(struct page *page)
}
static inline int f2fs_init_compress_mempool(void) { return 0; }
static inline void f2fs_destroy_compress_mempool(void) { }
+static inline void f2fs_end_read_compressed_page(struct page *page, bool failed)
+{
+ WARN_ON_ONCE(1);
+}
+static inline void f2fs_put_page_dic(struct page *page)
+{
+ WARN_ON_ONCE(1);
+}
static inline int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi) { return 0; }
static inline void f2fs_destroy_page_array_cache(struct f2fs_sb_info *sbi) { }
static inline int __init f2fs_init_compress_cache(void) { return 0; }
@@ -4114,6 +4147,12 @@ static inline bool f2fs_force_buffered_io(struct inode *inode,
return false;
}
+static inline bool f2fs_need_verity(const struct inode *inode, pgoff_t idx)
+{
+ return fsverity_active(inode) &&
+ idx < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
+}
+
#ifdef CONFIG_F2FS_FAULT_INJECTION
extern void f2fs_build_fault_attr(struct f2fs_sb_info *sbi, unsigned int rate,
unsigned int type);
base-commit: e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62
--
2.30.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [f2fs-dev] [PATCH v3] f2fs: clean up post-read processing
2021-01-05 6:33 [PATCH v3] f2fs: clean up post-read processing Eric Biggers
@ 2021-01-05 7:12 ` Chao Yu
0 siblings, 0 replies; 2+ messages in thread
From: Chao Yu @ 2021-01-05 7:12 UTC (permalink / raw)
To: Eric Biggers, linux-f2fs-devel; +Cc: linux-fscrypt
On 2021/1/5 14:33, Eric Biggers wrote:
> From: Eric Biggers<ebiggers@google.com>
>
> Rework the post-read processing logic to be much easier to understand.
>
> At least one bug is fixed by this: if an I/O error occurred when reading
> from disk, decryption and verity would be performed on the uninitialized
> data, causing misleading messages in the kernel log.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Thanks,
^ permalink raw reply [flat|nested] 2+ messages in thread
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