From 7716506adac4664793a9d6d3dfa31ffddfa98714 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox (Oracle) Date: Tue, 4 May 2021 18:32:45 -0700 Subject: mm: introduce and use mapping_empty() Patch series "Remove nrexceptional tracking", v2. We actually use nrexceptional for very little these days. It's a minor pain to keep in sync with nrpages, but the pain becomes much bigger with the THP patches because we don't know how many indices a shadow entry occupies. It's easier to just remove it than keep it accurate. Also, we save 8 bytes per inode which is nothing to sneeze at; on my laptop, it would improve shmem_inode_cache from 22 to 23 objects per 16kB, and inode_cache from 26 to 27 objects. Combined, that saves a megabyte of memory from a combined usage of 25MB for both caches. Unfortunately, ext4 doesn't cross a magic boundary, so it doesn't save any memory for ext4. This patch (of 4): Instead of checking the two counters (nrpages and nrexceptional), we can just check whether i_pages is empty. Link: https://lkml.kernel.org/r/20201026151849.24232-1-willy@infradead.org Link: https://lkml.kernel.org/r/20201026151849.24232-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Tested-by: Vishal Verma Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/block_dev.c | 2 +- fs/dax.c | 2 +- fs/gfs2/glock.c | 3 +-- 3 files changed, 3 insertions(+), 4 deletions(-) (limited to 'fs') diff --git a/fs/block_dev.c b/fs/block_dev.c index a5244e08b6c8..9114e0a0e7b4 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -79,7 +79,7 @@ static void kill_bdev(struct block_device *bdev) { struct address_space *mapping = bdev->bd_inode->i_mapping; - if (mapping->nrpages == 0 && mapping->nrexceptional == 0) + if (mapping_empty(mapping)) return; invalidate_bh_lrus(); diff --git a/fs/dax.c b/fs/dax.c index b3d27fdc6775..999f3f22aea3 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -965,7 +965,7 @@ int dax_writeback_mapping_range(struct address_space *mapping, if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) return -EIO; - if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) + if (mapping_empty(mapping) || wbc->sync_mode != WB_SYNC_ALL) return 0; trace_dax_writeback_range(inode, xas.xa_index, end_index); diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 84c38103aa06..ea7fc5c641c7 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -273,8 +273,7 @@ static void __gfs2_glock_put(struct gfs2_glock *gl) if (mapping) { truncate_inode_pages_final(mapping); if (!gfs2_withdrawn(sdp)) - GLOCK_BUG_ON(gl, mapping->nrpages || - mapping->nrexceptional); + GLOCK_BUG_ON(gl, !mapping_empty(mapping)); } trace_gfs2_glock_put(gl); sdp->sd_lockstruct.ls_ops->lm_put_lock(gl); -- cgit v1.2.3