From bb7f5d96aaa87d5aee2f5eb98ae0b84f08988489 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Mon, 7 Mar 2022 23:30:03 +0100 Subject: gfs2: Fix should_fault_in_pages() logic Fix the fault-in window size logic: * Use a maximum window size of 1 MiB instead of BIO_MAX_VECS * PAGE_SIZE. The previous window size was always one page because the pages variable was accidentally being defined and then redefined in should_fault_in_pages(). * The nr_dirtied heuristic for guessing when there might be memory pressure often results in very small window sizes. Don't let nr_dirtied drop below 8 pages (as btrfs does). * Compute the window size in units of bytes, not pages. * Account for page overlap (unaligned iterators). Signed-off-by: Andreas Gruenbacher --- fs/gfs2/file.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) (limited to 'fs/gfs2') diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c index a743a9eb602f..0c8cf10281da 100644 --- a/fs/gfs2/file.c +++ b/fs/gfs2/file.c @@ -775,8 +775,7 @@ static inline bool should_fault_in_pages(ssize_t ret, struct iov_iter *i, size_t *window_size) { size_t count = iov_iter_count(i); - char __user *p; - int pages = 1; + size_t size, offs; if (likely(!count)) return false; @@ -785,18 +784,20 @@ static inline bool should_fault_in_pages(ssize_t ret, struct iov_iter *i, if (!iter_is_iovec(i)) return false; + size = PAGE_SIZE; + offs = offset_in_page(i->iov[0].iov_base + i->iov_offset); if (*prev_count != count || !*window_size) { - int pages, nr_dirtied; + size_t nr_dirtied; - pages = min_t(int, BIO_MAX_VECS, DIV_ROUND_UP(count, PAGE_SIZE)); + size = ALIGN(offs + count, PAGE_SIZE); + size = min_t(size_t, size, SZ_1M); nr_dirtied = max(current->nr_dirtied_pause - - current->nr_dirtied, 1); - pages = min(pages, nr_dirtied); + current->nr_dirtied, 8); + size = min(size, nr_dirtied << PAGE_SHIFT); } *prev_count = count; - p = i->iov[0].iov_base + i->iov_offset; - *window_size = (size_t)PAGE_SIZE * pages - offset_in_page(p); + *window_size = size - offs; return true; } -- cgit v1.2.3