diff mbox series

[v2,1/4] mm: Introduce and use mapping_empty

Message ID 20201026151849.24232-2-willy@infradead.org (mailing list archive)
State New, archived
Headers show
Series Remove nrexceptional tracking | expand

Commit Message

Matthew Wilcox Oct. 26, 2020, 3:18 p.m. UTC 
Instead of checking the two counters (nrpages and nrexceptional), we
can just check whether i_pages is empty.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Vishal Verma <vishal.l.verma@intel.com>
---
 fs/block_dev.c          |  2 +-
 fs/dax.c                |  2 +-
 fs/gfs2/glock.c         |  3 +--
 include/linux/pagemap.h |  5 +++++
 mm/truncate.c           | 18 +++---------------
 5 files changed, 11 insertions(+), 19 deletions(-)

Comments

Johannes Weiner Jan. 21, 2021, 8:42 p.m. UTC | #1 
On Mon, Oct 26, 2020 at 03:18:46PM +0000, Matthew Wilcox (Oracle) wrote:
> Instead of checking the two counters (nrpages and nrexceptional), we
> can just check whether i_pages is empty.
> 
> 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>

Heh, I was looking for the fs/inode.c hunk here, because I remember
those BUG_ONs in the inode free path. Found it in the last patch - I
guess they escaped grep but the compiler let you know? :-)
Matthew Wilcox Jan. 21, 2021, 9:18 p.m. UTC | #2 
On Thu, Jan 21, 2021 at 03:42:31PM -0500, Johannes Weiner wrote:
> On Mon, Oct 26, 2020 at 03:18:46PM +0000, Matthew Wilcox (Oracle) wrote:
> > Instead of checking the two counters (nrpages and nrexceptional), we
> > can just check whether i_pages is empty.
> > 
> > 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>
> 
> Heh, I was looking for the fs/inode.c hunk here, because I remember
> those BUG_ONs in the inode free path. Found it in the last patch - I
> guess they escaped grep but the compiler let you know? :-)

Heh, I forget now!  I think I did it that way on purpose, but now I
forget what that purpose was!
diff mbox series

Patch

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9e84b1928b94..34105f66e12f 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 5b47834f2e1b..53ed0ab8c958 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 5441c17562c5..bfad01ce096d 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 dc3390e6ee3e..86143d36d028 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 11ef90d7e3af..58524aaf67e2 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -342,7 +342,7 @@  void truncate_inode_pages_range(struct address_space *mapping,
 	struct page *	page;
 	bool partial_end;
 
-	if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
+	if (mapping_empty(mapping))
 		goto out;
 
 	/*
@@ -470,9 +470,6 @@  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
@@ -482,16 +479,7 @@  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
@@ -657,7 +645,7 @@  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);