From 7e6cea5ae2f5e62112fce69acc07ee8b694b6dd0 Mon Sep 17 00:00:00 2001 From: Joanne Koong Date: Tue, 11 Nov 2025 11:36:52 -0800 Subject: docs: document iomap writeback's iomap_finish_folio_write() requirement Document that iomap_finish_folio_write() must be called after writeback on the range completes. Signed-off-by: Joanne Koong Link: https://patch.msgid.link/20251111193658.3495942-4-joannelkoong@gmail.com Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner --- include/linux/iomap.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux') diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 8b1ac08c7474..a5032e456079 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -435,6 +435,10 @@ struct iomap_writeback_ops { * An existing mapping from a previous call to this method can be reused * by the file system if it is still valid. * + * If this succeeds, iomap_finish_folio_write() must be called once + * writeback completes for the range, regardless of whether the + * writeback succeeded or failed. + * * Returns the number of bytes processed or a negative errno. */ ssize_t (*writeback_range)(struct iomap_writepage_ctx *wpc, -- cgit v1.2.3 From 6b1fd2281fb0873ec56f8791d4e4898302070804 Mon Sep 17 00:00:00 2001 From: Joanne Koong Date: Tue, 11 Nov 2025 11:36:53 -0800 Subject: iomap: optimize pending async writeback accounting Pending writebacks must be accounted for to determine when all requests have completed and writeback on the folio should be ended. Currently this is done by atomically incrementing ifs->write_bytes_pending for every range to be written back. Instead, the number of atomic operations can be minimized by setting ifs->write_bytes_pending to the folio size, internally tracking how many bytes are written back asynchronously, and then after sending off all the requests, decrementing ifs->write_bytes_pending by the number of bytes not written back asynchronously. Now, for N ranges written back, only N + 2 atomic operations are required instead of 2N + 2. Signed-off-by: Joanne Koong Link: https://patch.msgid.link/20251111193658.3495942-5-joannelkoong@gmail.com Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner --- include/linux/iomap.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/iomap.h b/include/linux/iomap.h index a5032e456079..b49e47f069db 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -478,8 +478,6 @@ int iomap_ioend_writeback_submit(struct iomap_writepage_ctx *wpc, int error); void iomap_finish_folio_read(struct folio *folio, size_t off, size_t len, int error); -void iomap_start_folio_write(struct inode *inode, struct folio *folio, - size_t len); void iomap_finish_folio_write(struct inode *inode, struct folio *folio, size_t len); -- cgit v1.2.3 From f8eaf79406fe9415db0e7a5c175b50cb01265199 Mon Sep 17 00:00:00 2001 From: Joanne Koong Date: Tue, 11 Nov 2025 11:36:54 -0800 Subject: iomap: simplify ->read_folio_range() error handling for reads Instead of requiring that the caller calls iomap_finish_folio_read() even if the ->read_folio_range() callback returns an error, account for this internally in iomap instead, which makes the interface simpler and makes it match writeback's ->read_folio_range() error handling expectations. Signed-off-by: Joanne Koong Link: https://patch.msgid.link/20251111193658.3495942-6-joannelkoong@gmail.com Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner --- include/linux/iomap.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/iomap.h b/include/linux/iomap.h index b49e47f069db..520e967cb501 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -495,9 +495,8 @@ struct iomap_read_ops { /* * Read in a folio range. * - * The caller is responsible for calling iomap_finish_folio_read() after - * reading in the folio range. This should be done even if an error is - * encountered during the read. + * If this succeeds, iomap_finish_folio_read() must be called after the + * range is read in, regardless of whether the read succeeded or failed. * * Returns 0 on success or a negative error on failure. */ -- cgit v1.2.3