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authorMatthew Wilcox (Oracle) <willy@infradead.org>2021-05-05 03:32:45 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 20:27:19 +0200
commit7716506adac4664793a9d6d3dfa31ffddfa98714 (patch)
treeec099a414e8120e3e68e2e6022eed8fa6fff5a3b
parentmm/memory-failure: unnecessary amount of unmapping (diff)
downloadlinux-7716506adac4664793a9d6d3dfa31ffddfa98714.tar.xz
linux-7716506adac4664793a9d6d3dfa31ffddfa98714.zip
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) <willy@infradead.org> Tested-by: Vishal Verma <vishal.l.verma@intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/block_dev.c2
-rw-r--r--fs/dax.c2
-rw-r--r--fs/gfs2/glock.c3
-rw-r--r--include/linux/pagemap.h5
-rw-r--r--mm/truncate.c18
5 files changed, 11 insertions, 19 deletions
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);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 469fa7ffcf96..a4bd41128bf3 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -18,6 +18,11 @@
struct pagevec;
+static inline bool mapping_empty(struct address_space *mapping)
+{
+ return xa_empty(&mapping->i_pages);
+}
+
/*
* Bits in mapping->flags.
*/
diff --git a/mm/truncate.c b/mm/truncate.c
index 455944264663..adb8d4107988 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -295,7 +295,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
pgoff_t index;
int i;
- if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
+ if (mapping_empty(mapping))
goto out;
/* Offsets within partial pages */
@@ -440,9 +440,6 @@ EXPORT_SYMBOL(truncate_inode_pages);
*/
void truncate_inode_pages_final(struct address_space *mapping)
{
- unsigned long nrexceptional;
- unsigned long nrpages;
-
/*
* Page reclaim can not participate in regular inode lifetime
* management (can't call iput()) and thus can race with the
@@ -452,16 +449,7 @@ void truncate_inode_pages_final(struct address_space *mapping)
*/
mapping_set_exiting(mapping);
- /*
- * When reclaim installs eviction entries, it increases
- * nrexceptional first, then decreases nrpages. Make sure we see
- * this in the right order or we might miss an entry.
- */
- nrpages = mapping->nrpages;
- smp_rmb();
- nrexceptional = mapping->nrexceptional;
-
- if (nrpages || nrexceptional) {
+ if (!mapping_empty(mapping)) {
/*
* As truncation uses a lockless tree lookup, cycle
* the tree lock to make sure any ongoing tree
@@ -633,7 +621,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
int ret2 = 0;
int did_range_unmap = 0;
- if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
+ if (mapping_empty(mapping))
goto out;
pagevec_init(&pvec);