In prep for the following support for readahead for page cache sharing,
we need accurate inode size of the anonymous inode, or the readahead
algorithm may exceed EOF of blobs if the inode size is OFFSET_MAX magic.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/fscache.c  | 9 +++++++++
 fs/erofs/internal.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index bed02b21978a..4fe7f23b022e 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -554,6 +554,15 @@ struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
 	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 	inode->i_private = ctx;
 
+	if (test_opt(&EROFS_SB(sb)->opt, SHARE_CACHE)) {
+		struct netfs_cache_resources cres;
+		ret = fscache_begin_read_operation(&cres, cookie);
+		if (ret)
+			goto err_cookie;
+		fscache_end_operation(&cres);
+		inode->i_size = cookie->object_size;
+	}
+
 	ctx->cookie = cookie;
 	ctx->inode = inode;
 	return ctx;
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 7c6a7a2d9acf..60d14561fb46 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -181,6 +181,7 @@ struct erofs_sb_info {
 #define EROFS_MOUNT_POSIX_ACL		0x00000020
 #define EROFS_MOUNT_DAX_ALWAYS		0x00000040
 #define EROFS_MOUNT_DAX_NEVER		0x00000080
+#define EROFS_MOUNT_SHARE_CACHE		0x00000100
 
 #define clear_opt(opt, option)	((opt)->mount_opt &= ~EROFS_MOUNT_##option)
 #define set_opt(opt, option)	((opt)->mount_opt |= EROFS_MOUNT_##option)
-- 
2.19.1.6.gb485710b