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Mon, 22 Sep 2025 17:34:02 -0700 (PDT) From: Joanne Koong To: brauner@kernel.org, miklos@szeredi.hu Cc: djwong@kernel.org, hch@infradead.org, linux-block@vger.kernel.org, gfs2@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-doc@vger.kernel.org, hsiangkao@linux.alibaba.com, kernel-team@meta.com Subject: [PATCH v4 07/15] iomap: track read/readahead folio ownership internally Date: Mon, 22 Sep 2025 17:23:45 -0700 Message-ID: <20250923002353.2961514-8-joannelkoong@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250923002353.2961514-1-joannelkoong@gmail.com> References: <20250923002353.2961514-1-joannelkoong@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The purpose of "struct iomap_read_folio_ctx->cur_folio_in_bio" is to track folio ownership to know who is responsible for unlocking it. Rename "cur_folio_in_bio" to "cur_folio_owned" to better reflect this purpose and so that this can be generically used later on by filesystems that are not block-based. Since "struct iomap_read_folio_ctx" will be made a public interface later on when read/readahead takes in caller-provided callbacks, track the folio ownership state internally instead of exposing it in "struct iomap_read_folio_ctx" to make the interface simpler for end users. Signed-off-by: Joanne Koong --- fs/iomap/buffered-io.c | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 09e65771a947..34df1cddf65c 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -362,7 +362,6 @@ static void iomap_read_end_io(struct bio *bio) struct iomap_read_folio_ctx { struct folio *cur_folio; - bool cur_folio_in_bio; void *read_ctx; struct readahead_control *rac; }; @@ -386,7 +385,6 @@ static void iomap_bio_read_folio_range(const struct iomap_iter *iter, sector_t sector; struct bio *bio = ctx->read_ctx; - ctx->cur_folio_in_bio = true; if (ifs) { spin_lock_irq(&ifs->state_lock); ifs->read_bytes_pending += plen; @@ -423,7 +421,7 @@ static void iomap_bio_read_folio_range(const struct iomap_iter *iter, } static int iomap_read_folio_iter(struct iomap_iter *iter, - struct iomap_read_folio_ctx *ctx) + struct iomap_read_folio_ctx *ctx, bool *folio_owned) { const struct iomap *iomap = &iter->iomap; loff_t pos = iter->pos; @@ -460,6 +458,7 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, folio_zero_range(folio, poff, plen); iomap_set_range_uptodate(folio, poff, plen); } else { + *folio_owned = true; iomap_bio_read_folio_range(iter, ctx, pos, plen); } @@ -482,16 +481,22 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) struct iomap_read_folio_ctx ctx = { .cur_folio = folio, }; + /* + * If an IO helper takes ownership of the folio, it is responsible for + * unlocking it when the read completes. + */ + bool folio_owned = false; int ret; trace_iomap_readpage(iter.inode, 1); while ((ret = iomap_iter(&iter, ops)) > 0) - iter.status = iomap_read_folio_iter(&iter, &ctx); + iter.status = iomap_read_folio_iter(&iter, &ctx, + &folio_owned); iomap_bio_submit_read(&ctx); - if (!ctx.cur_folio_in_bio) + if (!folio_owned) folio_unlock(folio); /* @@ -504,14 +509,15 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) EXPORT_SYMBOL_GPL(iomap_read_folio); static int iomap_readahead_iter(struct iomap_iter *iter, - struct iomap_read_folio_ctx *ctx) + struct iomap_read_folio_ctx *ctx, + bool *cur_folio_owned) { int ret; while (iomap_length(iter)) { if (ctx->cur_folio && offset_in_folio(ctx->cur_folio, iter->pos) == 0) { - if (!ctx->cur_folio_in_bio) + if (!*cur_folio_owned) folio_unlock(ctx->cur_folio); ctx->cur_folio = NULL; } @@ -519,9 +525,9 @@ static int iomap_readahead_iter(struct iomap_iter *iter, ctx->cur_folio = readahead_folio(ctx->rac); if (WARN_ON_ONCE(!ctx->cur_folio)) return -EINVAL; - ctx->cur_folio_in_bio = false; + *cur_folio_owned = false; } - ret = iomap_read_folio_iter(iter, ctx); + ret = iomap_read_folio_iter(iter, ctx, cur_folio_owned); if (ret) return ret; } @@ -554,15 +560,21 @@ void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops) struct iomap_read_folio_ctx ctx = { .rac = rac, }; + /* + * If an IO helper takes ownership of the folio, it is responsible for + * unlocking it when the read completes. + */ + bool cur_folio_owned = false; trace_iomap_readahead(rac->mapping->host, readahead_count(rac)); while (iomap_iter(&iter, ops) > 0) - iter.status = iomap_readahead_iter(&iter, &ctx); + iter.status = iomap_readahead_iter(&iter, &ctx, + &cur_folio_owned); iomap_bio_submit_read(&ctx); - if (ctx.cur_folio && !ctx.cur_folio_in_bio) + if (ctx.cur_folio && !cur_folio_owned) folio_unlock(ctx.cur_folio); } EXPORT_SYMBOL_GPL(iomap_readahead); -- 2.47.3