erofs: support compressed inodes for page cache share

This patch adds page cache sharing functionality for compressed inodes.

Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Author: Hongzhen Luo

fs/erofs/ishare.c

@@ -44,8 +44,6 @@ bool erofs_ishare_fill_inode(struct inode *inode)
 	struct inode *sharedinode;
 	unsigned long hash;
 
-	if (erofs_inode_is_data_compressed(vi->datalayout))
-		return false;
 	if (erofs_xattr_fill_inode_fingerprint(&fp, inode, sbi->domain_id))
 		return false;
 	hash = xxh32(fp.opaque, fp.size, 0);

fs/erofs/zdata.c

@@ -494,7 +494,7 @@ enum z_erofs_pclustermode {
 };
 
 struct z_erofs_frontend {
-	struct inode *const inode;
+	struct inode *inode, *sharedinode;
 	struct erofs_map_blocks map;
 	struct z_erofs_bvec_iter biter;
 
@@ -509,8 +509,8 @@ struct z_erofs_frontend {
 	unsigned int icur;
 };
 
-#define Z_EROFS_DEFINE_FRONTEND(fe, i, ho) struct z_erofs_frontend fe = { \
-	.inode = i, .head = Z_EROFS_PCLUSTER_TAIL, \
+#define Z_EROFS_DEFINE_FRONTEND(fe, i, si, ho) struct z_erofs_frontend fe = { \
+	.inode = i, .sharedinode = si, .head = Z_EROFS_PCLUSTER_TAIL, \
 	.mode = Z_EROFS_PCLUSTER_FOLLOWED, .headoffset = ho }
 
 static bool z_erofs_should_alloc_cache(struct z_erofs_frontend *fe)
@@ -1858,7 +1858,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,
 		pgoff_t index = cur >> PAGE_SHIFT;
 		struct folio *folio;
 
-		folio = erofs_grab_folio_nowait(inode->i_mapping, index);
+		folio = erofs_grab_folio_nowait(f->sharedinode->i_mapping, index);
 		if (!IS_ERR_OR_NULL(folio)) {
 			if (folio_test_uptodate(folio))
 				folio_unlock(folio);
@@ -1875,11 +1875,13 @@ static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,
 
 static int z_erofs_read_folio(struct file *file, struct folio *folio)
 {
-	struct inode *const inode = folio->mapping->host;
-	Z_EROFS_DEFINE_FRONTEND(f, inode, folio_pos(folio));
+	struct inode *sharedinode = folio->mapping->host;
+	bool need_iput;
+	struct inode *realinode = erofs_real_inode(sharedinode, &need_iput);
+	Z_EROFS_DEFINE_FRONTEND(f, realinode, sharedinode, folio_pos(folio));
 	int err;
 
-	trace_erofs_read_folio(inode, folio, false);
+	trace_erofs_read_folio(realinode, folio, false);
 	z_erofs_pcluster_readmore(&f, NULL, true);
 	err = z_erofs_scan_folio(&f, folio, false);
 	z_erofs_pcluster_readmore(&f, NULL, false);
@@ -1888,23 +1890,28 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
 	/* if some pclusters are ready, need submit them anyway */
 	err = z_erofs_runqueue(&f, 0) ?: err;
 	if (err && err != -EINTR)
-		erofs_err(inode->i_sb, "read error %d @ %lu of nid %llu",
-			  err, folio->index, EROFS_I(inode)->nid);
+		erofs_err(realinode->i_sb, "read error %d @ %lu of nid %llu",
+			  err, folio->index, EROFS_I(realinode)->nid);
 
 	erofs_put_metabuf(&f.map.buf);
 	erofs_release_pages(&f.pagepool);
+
+	if (need_iput)
+		iput(realinode);
 	return err;
 }
 
 static void z_erofs_readahead(struct readahead_control *rac)
 {
-	struct inode *const inode = rac->mapping->host;
-	Z_EROFS_DEFINE_FRONTEND(f, inode, readahead_pos(rac));
+	struct inode *sharedinode = rac->mapping->host;
+	bool need_iput;
+	struct inode *realinode = erofs_real_inode(sharedinode, &need_iput);
+	Z_EROFS_DEFINE_FRONTEND(f, realinode, sharedinode, readahead_pos(rac));
 	unsigned int nrpages = readahead_count(rac);
 	struct folio *head = NULL, *folio;
 	int err;
 
-	trace_erofs_readahead(inode, readahead_index(rac), nrpages, false);
+	trace_erofs_readahead(realinode, readahead_index(rac), nrpages, false);
 	z_erofs_pcluster_readmore(&f, rac, true);
 	while ((folio = readahead_folio(rac))) {
 		folio->private = head;
@@ -1918,15 +1925,18 @@ static void z_erofs_readahead(struct readahead_control *rac)
 
 		err = z_erofs_scan_folio(&f, folio, true);
 		if (err && err != -EINTR)
-			erofs_err(inode->i_sb, "readahead error at folio %lu @ nid %llu",
-				  folio->index, EROFS_I(inode)->nid);
+			erofs_err(realinode->i_sb, "readahead error at folio %lu @ nid %llu",
+				  folio->index, EROFS_I(realinode)->nid);
 	}
 	z_erofs_pcluster_readmore(&f, rac, false);
 	z_erofs_pcluster_end(&f);
 
 	(void)z_erofs_runqueue(&f, nrpages << PAGE_SHIFT);
 	erofs_put_metabuf(&f.map.buf);
 	erofs_release_pages(&f.pagepool);
+
+	if (need_iput)
+		iput(realinode);
 }
 
 const struct address_space_operations z_erofs_aops = {