[13/21] xfs: don't allow highmem pages in xfile mappings

Commit Message

Christoph Hellwig Jan. 26, 2024, 1:28 p.m. UTC

XFS is generally used on 64-bit, non-highmem platforms and xfile
mappings are accessed all the time.  Reduce our pain by not allowing
any highmem mappings in the xfile page cache and remove all the kmap
calls for it.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Darrick J. Wong <[e-mail]>
---
 fs/xfs/scrub/xfarray.c |  3 +--
 fs/xfs/scrub/xfile.c   | 21 +++++++++------------
 2 files changed, 10 insertions(+), 14 deletions(-)

Comments

Matthew Wilcox Jan. 26, 2024, 4:26 p.m. UTC | #1

On Fri, Jan 26, 2024 at 02:28:55PM +0100, Christoph Hellwig wrote:
> XFS is generally used on 64-bit, non-highmem platforms and xfile
> mappings are accessed all the time.  Reduce our pain by not allowing
> any highmem mappings in the xfile page cache and remove all the kmap
> calls for it.

Ummm ...

> +++ b/fs/xfs/scrub/xfile.c
> @@ -77,6 +77,12 @@ xfile_create(
>  	inode = file_inode(xf->file);
>  	lockdep_set_class(&inode->i_rwsem, &xfile_i_mutex_key);
>  
> +	/*
> +	 * We don't want to bother with kmapping data during repair, so don't
> +	 * allow highmem pages to back this mapping.
> +	 */
> +	mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);

HIGHUSER includes __GFP_HIGHMEM.

Do you want GFP_USER?  Compared to GFP_KERNEL, it includes the "cpuset
memory allocation policy" which ... I have no idea what it means, honestly.

Patch

diff --git a/fs/xfs/scrub/xfarray.c b/fs/xfs/scrub/xfarray.c
index 95ac14bceeadd6..d0f98a43b2ba0a 100644
--- a/fs/xfs/scrub/xfarray.c
+++ b/fs/xfs/scrub/xfarray.c
@@ -580,7 +580,7 @@  xfarray_sort_get_page(
 	 * xfile pages must never be mapped into userspace, so we skip the
 	 * dcache flush when mapping the page.
 	 */
-	si->page_kaddr = kmap_local_page(si->xfpage.page);
+	si->page_kaddr = page_address(si->xfpage.page);
 	return 0;
 }
 
@@ -592,7 +592,6 @@  xfarray_sort_put_page(
 	if (!si->page_kaddr)
 		return 0;
 
-	kunmap_local(si->page_kaddr);
 	si->page_kaddr = NULL;
 
 	return xfile_put_page(si->array->xfile, &si->xfpage);
diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
index 7e915385ef0011..623bbde91ae3fe 100644
--- a/fs/xfs/scrub/xfile.c
+++ b/fs/xfs/scrub/xfile.c
@@ -77,6 +77,12 @@  xfile_create(
 	inode = file_inode(xf->file);
 	lockdep_set_class(&inode->i_rwsem, &xfile_i_mutex_key);
 
+	/*
+	 * We don't want to bother with kmapping data during repair, so don't
+	 * allow highmem pages to back this mapping.
+	 */
+	mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
+
 	trace_xfile_create(xf);
 
 	*xfilep = xf;
@@ -126,7 +132,6 @@  xfile_load(
 
 	pflags = memalloc_nofs_save();
 	while (count > 0) {
-		void		*p, *kaddr;
 		unsigned int	len;
 
 		len = min_t(ssize_t, count, PAGE_SIZE - offset_in_page(pos));
@@ -153,10 +158,7 @@  xfile_load(
 		 * xfile pages must never be mapped into userspace, so
 		 * we skip the dcache flush.
 		 */
-		kaddr = kmap_local_page(page);
-		p = kaddr + offset_in_page(pos);
-		memcpy(buf, p, len);
-		kunmap_local(kaddr);
+		memcpy(buf, page_address(page) + offset_in_page(pos), len);
 		put_page(page);
 
 advance:
@@ -221,14 +223,13 @@  xfile_store(
 		 * the dcache flush.  If the page is not uptodate, zero it
 		 * before writing data.
 		 */
-		kaddr = kmap_local_page(page);
+		kaddr = page_address(page);
 		if (!PageUptodate(page)) {
 			memset(kaddr, 0, PAGE_SIZE);
 			SetPageUptodate(page);
 		}
 		p = kaddr + offset_in_page(pos);
 		memcpy(p, buf, len);
-		kunmap_local(kaddr);
 
 		ret = aops->write_end(NULL, mapping, pos, len, len, page,
 				fsdata);
@@ -314,11 +315,7 @@  xfile_get_page(
 	 * to the caller and make sure the backing store will hold on to them.
 	 */
 	if (!PageUptodate(page)) {
-		void	*kaddr;
-
-		kaddr = kmap_local_page(page);
-		memset(kaddr, 0, PAGE_SIZE);
-		kunmap_local(kaddr);
+		memset(page_address(page), 0, PAGE_SIZE);
 		SetPageUptodate(page);
 	}