From 670d21c6e17f67535fcf16e14c772209220da9ae Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 22 Mar 2022 14:38:58 -0700 Subject: fuse: remove reliance on bdi congestion The bdi congestion tracking in not widely used and will be removed. Fuse is one of a small number of filesystems that uses it, setting both the sync (read) and async (write) congestion flags at what it determines are appropriate times. The only remaining effect of the sync flag is to cause read-ahead to be skipped. The only remaining effect of the async flag is to cause (some) WB_SYNC_NONE writes to be skipped. So instead of setting the flags, change: - .readahead to stop when it has submitted all non-async pages for read. - .writepages to do nothing if WB_SYNC_NONE and the flag would be set - .writepage to return AOP_WRITEPAGE_ACTIVATE if WB_SYNC_NONE and the flag would be set. The writepages change causes a behavioural change in that pageout() can now return PAGE_ACTIVATE instead of PAGE_KEEP, so SetPageActive() will be called on the page which (I think) will further delay the next attempt at writeout. This might be a good thing. Link: https://lkml.kernel.org/r/164549983737.9187.2627117501000365074.stgit@noble.brown Signed-off-by: NeilBrown Cc: Anna Schumaker Cc: Chao Yu Cc: Darrick J. Wong Cc: Ilya Dryomov Cc: Jaegeuk Kim Cc: Jan Kara Cc: Jeff Layton Cc: Jens Axboe Cc: Lars Ellenberg Cc: Miklos Szeredi Cc: Paolo Valente Cc: Philipp Reisner Cc: Ryusuke Konishi Cc: Trond Myklebust Cc: Wu Fengguang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/control.c | 17 ----------------- fs/fuse/dev.c | 8 -------- fs/fuse/file.c | 17 +++++++++++++++++ 3 files changed, 17 insertions(+), 25 deletions(-) (limited to 'fs/fuse') diff --git a/fs/fuse/control.c b/fs/fuse/control.c index 000d2e5627e9..7cede9a3bc96 100644 --- a/fs/fuse/control.c +++ b/fs/fuse/control.c @@ -164,7 +164,6 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file, { unsigned val; struct fuse_conn *fc; - struct fuse_mount *fm; ssize_t ret; ret = fuse_conn_limit_write(file, buf, count, ppos, &val, @@ -178,22 +177,6 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file, down_read(&fc->killsb); spin_lock(&fc->bg_lock); fc->congestion_threshold = val; - - /* - * Get any fuse_mount belonging to this fuse_conn; s_bdi is - * shared between all of them - */ - - if (!list_empty(&fc->mounts)) { - fm = list_first_entry(&fc->mounts, struct fuse_mount, fc_entry); - if (fc->num_background < fc->congestion_threshold) { - clear_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); - clear_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); - } else { - set_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); - set_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); - } - } spin_unlock(&fc->bg_lock); up_read(&fc->killsb); fuse_conn_put(fc); diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 592730fd6e42..0e537e580dc1 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -315,10 +315,6 @@ void fuse_request_end(struct fuse_req *req) wake_up(&fc->blocked_waitq); } - if (fc->num_background == fc->congestion_threshold && fm->sb) { - clear_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); - clear_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); - } fc->num_background--; fc->active_background--; flush_bg_queue(fc); @@ -540,10 +536,6 @@ static bool fuse_request_queue_background(struct fuse_req *req) fc->num_background++; if (fc->num_background == fc->max_background) fc->blocked = 1; - if (fc->num_background == fc->congestion_threshold && fm->sb) { - set_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); - set_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); - } list_add_tail(&req->list, &fc->bg_queue); flush_bg_queue(fc); queued = true; diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 0fc150c1c50b..61b1e04eb497 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -966,6 +966,14 @@ static void fuse_readahead(struct readahead_control *rac) struct fuse_io_args *ia; struct fuse_args_pages *ap; + if (fc->num_background >= fc->congestion_threshold && + rac->ra->async_size >= readahead_count(rac)) + /* + * Congested and only async pages left, so skip the + * rest. + */ + break; + nr_pages = readahead_count(rac) - nr_pages; if (nr_pages > max_pages) nr_pages = max_pages; @@ -1959,6 +1967,7 @@ err: static int fuse_writepage(struct page *page, struct writeback_control *wbc) { + struct fuse_conn *fc = get_fuse_conn(page->mapping->host); int err; if (fuse_page_is_writeback(page->mapping->host, page->index)) { @@ -1974,6 +1983,10 @@ static int fuse_writepage(struct page *page, struct writeback_control *wbc) return 0; } + if (wbc->sync_mode == WB_SYNC_NONE && + fc->num_background >= fc->congestion_threshold) + return AOP_WRITEPAGE_ACTIVATE; + err = fuse_writepage_locked(page); unlock_page(page); @@ -2227,6 +2240,10 @@ static int fuse_writepages(struct address_space *mapping, if (fuse_is_bad(inode)) goto out; + if (wbc->sync_mode == WB_SYNC_NONE && + fc->num_background >= fc->congestion_threshold) + return 0; + data.inode = inode; data.wpa = NULL; data.ff = NULL; -- cgit v1.2.3