From 4e4cbee93d56137ebff722be022cae5f70ef84fb Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sat, 3 Jun 2017 09:38:06 +0200 Subject: block: switch bios to blk_status_t Replace bi_error with a new bi_status to allow for a clear conversion. Note that device mapper overloaded bi_error with a private value, which we'll have to keep arround at least for now and thus propagate to a proper blk_status_t value. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- mm/page_io.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/page_io.c b/mm/page_io.c index 23f6d0d3470f..2da71e627812 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -45,7 +45,7 @@ void end_swap_bio_write(struct bio *bio) { struct page *page = bio->bi_io_vec[0].bv_page; - if (bio->bi_error) { + if (bio->bi_status) { SetPageError(page); /* * We failed to write the page out to swap-space. @@ -118,7 +118,7 @@ static void end_swap_bio_read(struct bio *bio) { struct page *page = bio->bi_io_vec[0].bv_page; - if (bio->bi_error) { + if (bio->bi_status) { SetPageError(page); ClearPageUptodate(page); pr_alert("Read-error on swap-device (%u:%u:%llu)\n", -- cgit v1.2.3 From 7fc9e4722435cd8459182c4975f48934f2bb1274 Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Tue, 20 Jun 2017 07:05:41 -0500 Subject: fs: Introduce filemap_range_has_page() filemap_range_has_page() return true if the file's mapping has a page within the range mentioned. This function will be used to check if a write() call will cause a writeback of previous writes. Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Goldwyn Rodrigues Signed-off-by: Jens Axboe --- include/linux/fs.h | 2 ++ mm/filemap.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+) (limited to 'mm') diff --git a/include/linux/fs.h b/include/linux/fs.h index 96a1a1fa54a9..0d34f5b5a6b0 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2518,6 +2518,8 @@ extern int filemap_fdatawait(struct address_space *); extern void filemap_fdatawait_keep_errors(struct address_space *); extern int filemap_fdatawait_range(struct address_space *, loff_t lstart, loff_t lend); +extern bool filemap_range_has_page(struct address_space *, loff_t lstart, + loff_t lend); extern int filemap_write_and_wait(struct address_space *mapping); extern int filemap_write_and_wait_range(struct address_space *mapping, loff_t lstart, loff_t lend); diff --git a/mm/filemap.c b/mm/filemap.c index 6f1be573a5e6..9b39a2390b9e 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -376,6 +376,38 @@ int filemap_flush(struct address_space *mapping) } EXPORT_SYMBOL(filemap_flush); +/** + * filemap_range_has_page - check if a page exists in range. + * @mapping: address space within which to check + * @start_byte: offset in bytes where the range starts + * @end_byte: offset in bytes where the range ends (inclusive) + * + * Find at least one page in the range supplied, usually used to check if + * direct writing in this range will trigger a writeback. + */ +bool filemap_range_has_page(struct address_space *mapping, + loff_t start_byte, loff_t end_byte) +{ + pgoff_t index = start_byte >> PAGE_SHIFT; + pgoff_t end = end_byte >> PAGE_SHIFT; + struct pagevec pvec; + bool ret; + + if (end_byte < start_byte) + return false; + + if (mapping->nrpages == 0) + return false; + + pagevec_init(&pvec, 0); + if (!pagevec_lookup(&pvec, mapping, index, 1)) + return false; + ret = (pvec.pages[0]->index <= end); + pagevec_release(&pvec); + return ret; +} +EXPORT_SYMBOL(filemap_range_has_page); + static int __filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, loff_t end_byte) { -- cgit v1.2.3 From 6be96d3ad34a124450028dabba43f07fe1d0c86d Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Tue, 20 Jun 2017 07:05:44 -0500 Subject: fs: return if direct I/O will trigger writeback Find out if the I/O will trigger a wait due to writeback. If yes, return -EAGAIN. Return -EINVAL for buffered AIO: there are multiple causes of delay such as page locks, dirty throttling logic, page loading from disk etc. which cannot be taken care of. Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Goldwyn Rodrigues Signed-off-by: Jens Axboe --- mm/filemap.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) (limited to 'mm') diff --git a/mm/filemap.c b/mm/filemap.c index 9b39a2390b9e..742034e56100 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2070,10 +2070,17 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) loff_t size; size = i_size_read(inode); - retval = filemap_write_and_wait_range(mapping, iocb->ki_pos, - iocb->ki_pos + count - 1); - if (retval < 0) - goto out; + if (iocb->ki_flags & IOCB_NOWAIT) { + if (filemap_range_has_page(mapping, iocb->ki_pos, + iocb->ki_pos + count - 1)) + return -EAGAIN; + } else { + retval = filemap_write_and_wait_range(mapping, + iocb->ki_pos, + iocb->ki_pos + count - 1); + if (retval < 0) + goto out; + } file_accessed(file); @@ -2674,6 +2681,9 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from) pos = iocb->ki_pos; + if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT)) + return -EINVAL; + if (limit != RLIM_INFINITY) { if (iocb->ki_pos >= limit) { send_sig(SIGXFSZ, current, 0); @@ -2742,9 +2752,17 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) write_len = iov_iter_count(from); end = (pos + write_len - 1) >> PAGE_SHIFT; - written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); - if (written) - goto out; + if (iocb->ki_flags & IOCB_NOWAIT) { + /* If there are pages to writeback, return */ + if (filemap_range_has_page(inode->i_mapping, pos, + pos + iov_iter_count(from))) + return -EAGAIN; + } else { + written = filemap_write_and_wait_range(mapping, pos, + pos + write_len - 1); + if (written) + goto out; + } /* * After a write we want buffered reads to be sure to go to disk to get -- cgit v1.2.3