erofs: get rid of fe->backmost for cache decompression

EROFS_MAP_FULL_MAPPED is more accurate to decide if caching the last
incomplete pcluster for later read or not.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-6-hsiangkao@linux.alibaba.com

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 82834e3..7e55e95 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -528,8 +528,6 @@ struct z_erofs_decompress_frontend {
        z_erofs_next_pcluster_t owned_head;
        enum z_erofs_pclustermode mode;
 
-       /* used for applying cache strategy on the fly */
-       bool backmost;
        erofs_off_t headoffset;
 
        /* a pointer used to pick up inplace I/O pages */
@@ -538,7 +536,7 @@ struct z_erofs_decompress_frontend {
 
 #define DECOMPRESS_FRONTEND_INIT(__i) { \
        .inode = __i, .owned_head = Z_EROFS_PCLUSTER_TAIL, \
-       .mode = Z_EROFS_PCLUSTER_FOLLOWED, .backmost = true }
+       .mode = Z_EROFS_PCLUSTER_FOLLOWED }
 
 static bool z_erofs_should_alloc_cache(struct z_erofs_decompress_frontend *fe)
 {
@@ -547,7 +545,7 @@ static bool z_erofs_should_alloc_cache(struct z_erofs_decompress_frontend *fe)
        if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
                return false;
 
-       if (fe->backmost)
+       if (!(fe->map.m_flags & EROFS_MAP_FULL_MAPPED))
                return true;
 
        if (cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
@@ -940,7 +938,6 @@ static void z_erofs_pcluster_end(struct z_erofs_decompress_frontend *fe)
                erofs_workgroup_put(&pcl->obj);
 
        fe->pcl = NULL;
-       fe->backmost = false;
 }
 
 static int z_erofs_read_fragment(struct super_block *sb, struct page *page,