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Thu, 25 Sep 2025 17:29:37 -0700 (PDT) From: Joanne Koong To: brauner@kernel.org, miklos@szeredi.hu Cc: djwong@kernel.org, hch@infradead.org, hsiangkao@linux.alibaba.com, linux-block@vger.kernel.org, gfs2@lists.linux.dev, linux-fsdevel@vger.kernel.org, kernel-team@meta.com, linux-xfs@vger.kernel.org, linux-doc@vger.kernel.org, Christoph Hellwig Subject: [PATCH v5 08/14] iomap: set accurate iter->pos when reading folio ranges Date: Thu, 25 Sep 2025 17:26:03 -0700 Message-ID: <20250926002609.1302233-9-joannelkoong@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250926002609.1302233-1-joannelkoong@gmail.com> References: <20250926002609.1302233-1-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 Advance iter to the correct position before calling an IO helper to read in a folio range. This allows the helper to reliably use iter->pos to determine the starting offset for reading. This will simplify the interface for reading in folio ranges when iomap read/readahead supports caller-provided callbacks. Signed-off-by: Joanne Koong Suggested-by: Christoph Hellwig --- fs/iomap/buffered-io.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 4e6258fdb915..82bdf7c5e03c 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -375,10 +375,11 @@ static void iomap_bio_submit_read(struct iomap_read_folio_ctx *ctx) } static void iomap_bio_read_folio_range(const struct iomap_iter *iter, - struct iomap_read_folio_ctx *ctx, loff_t pos, size_t plen) + struct iomap_read_folio_ctx *ctx, size_t plen) { struct folio *folio = ctx->cur_folio; const struct iomap *iomap = &iter->iomap; + loff_t pos = iter->pos; size_t poff = offset_in_folio(folio, pos); loff_t length = iomap_length(iter); sector_t sector; @@ -470,7 +471,7 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, loff_t length = iomap_length(iter); struct folio *folio = ctx->cur_folio; size_t poff, plen; - loff_t count; + loff_t pos_diff; int ret; if (iomap->type == IOMAP_INLINE) { @@ -488,12 +489,16 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, iomap_adjust_read_range(iter->inode, folio, &pos, length, &poff, &plen); - count = pos - iter->pos + plen; - if (WARN_ON_ONCE(count > length)) + pos_diff = pos - iter->pos; + if (WARN_ON_ONCE(pos_diff + plen > length)) return -EIO; + ret = iomap_iter_advance(iter, pos_diff); + if (ret) + return ret; + if (plen == 0) - return iomap_iter_advance(iter, count); + return 0; /* zero post-eof blocks as the page may be mapped */ if (iomap_block_needs_zeroing(iter, pos)) { @@ -503,13 +508,13 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, if (!*bytes_pending) iomap_read_init(folio); *bytes_pending += plen; - iomap_bio_read_folio_range(iter, ctx, pos, plen); + iomap_bio_read_folio_range(iter, ctx, plen); } - ret = iomap_iter_advance(iter, count); + ret = iomap_iter_advance(iter, plen); if (ret) return ret; - length -= count; + length -= pos_diff + plen; pos = iter->pos; } return 0; -- 2.47.3