From a883120b2d19630d3be56bc9649a71299ccbf95d Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 7 Nov 2024 14:35:07 +1030 Subject: [PATCH] btrfs: open-code btrfs_copy_from_user() The function btrfs_copy_from_user() handles the folio dirtying for buffered write. The original design is to allow that function to handle multiple folios, but since commit c87c299776e4 ("btrfs: make buffered write to copy one page a time") there is no need to support multiple folios. So here open-code btrfs_copy_from_user() to copy_folio_from_iter_atomic() and flush_dcache_folio() calls. The short-copy check and revert are still kept as-is. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/file.c | 66 ++++++++++++++----------------------------------- 1 file changed, 18 insertions(+), 48 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index c61f210259d8..3c00dc48b925 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -38,52 +38,6 @@ #include "super.h" #include "print-tree.h" -/* - * Helper to fault in page and copy. This should go away and be replaced with - * calls into generic code. - */ -static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes, - struct folio *folio, struct iov_iter *i) -{ - size_t copied = 0; - size_t total_copied = 0; - int offset = offset_in_page(pos); - - while (write_bytes > 0) { - size_t count = min_t(size_t, PAGE_SIZE - offset, write_bytes); - /* - * Copy data from userspace to the current page - */ - copied = copy_folio_from_iter_atomic(folio, offset, count, i); - - /* Flush processor's dcache for this page */ - flush_dcache_folio(folio); - - /* - * if we get a partial write, we can end up with - * partially up to date page. These add - * a lot of complexity, so make sure they don't - * happen by forcing this copy to be retried. - * - * The rest of the btrfs_file_write code will fall - * back to page at a time copies after we return 0. - */ - if (unlikely(copied < count)) { - if (!folio_test_uptodate(folio)) { - iov_iter_revert(i, copied); - copied = 0; - } - if (!copied) - break; - } - - write_bytes -= copied; - total_copied += copied; - offset += copied; - } - return total_copied; -} - /* * Unlock folio after btrfs_file_write() is done with it. */ @@ -107,7 +61,7 @@ static void btrfs_drop_folio(struct btrfs_fs_info *fs_info, struct folio *folio, } /* - * After btrfs_copy_from_user(), update the following things for delalloc: + * After copy_folio_from_iter_atomic(), update the following things for delalloc: * - Mark newly dirtied folio as DELALLOC in the io tree. * Used to advise which range is to be written back. * - Mark modified folio as Uptodate/Dirty and not needing COW fixup @@ -1269,7 +1223,23 @@ again: break; } - copied = btrfs_copy_from_user(pos, write_bytes, folio, i); + copied = copy_folio_from_iter_atomic(folio, + offset_in_folio(folio, pos), write_bytes, i); + flush_dcache_folio(folio); + + /* + * If we get a partial write, we can end up with partially + * uptodate page. Although if sector size < page size we can + * handle it, but if it's not sector aligned it can cause + * a lot of complexity, so make sure they don't happen by + * forcing retry this copy. + */ + if (unlikely(copied < write_bytes)) { + if (!folio_test_uptodate(folio)) { + iov_iter_revert(i, copied); + copied = 0; + } + } num_sectors = BTRFS_BYTES_TO_BLKS(fs_info, reserve_bytes); dirty_sectors = round_up(copied + sector_offset, -- 2.50.1