[PATCH 1/2] erofs: clean up encoded map flags

- Remove EROFS_MAP_ENCODED since it was always set together with
  EROFS_MAP_MAPPED for compressed extents and checked redundantly;

- Replace the EROFS_MAP_FULL_MAPPED flag with the opposite
  EROFS_MAP_PARTIAL_MAPPED flag so that extents are implicitly
  fully mapped initially to simplify the logic;

- Make fragment extents independent of EROFS_MAP_MAPPED since
  they are not directly allocated on disk; thus fragment extents
  are no longer twisted with mapped extents.

Signed-off-by: Gao Xiang <[email protected]>
---
 fs/erofs/internal.h          | 23 +++++++++++------------
 fs/erofs/zdata.c             | 19 +++++++++----------
 fs/erofs/zmap.c              | 19 ++++++++++---------
 include/trace/events/erofs.h |  7 +++----
 4 files changed, 33 insertions(+), 35 deletions(-)

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index a4f0a42cf8c3..4792490161ec 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -360,20 +360,19 @@ static inline struct folio *erofs_grab_folio_nowait(struct address_space *as,
 			readahead_gfp_mask(as) & ~__GFP_RECLAIM);
 }
 
-/* Has a disk mapping */
-#define EROFS_MAP_MAPPED	0x0001
+/* Allocated on disk at @m_pa (e.g. NOT a fragment extent) */
+#define EROFS_MAP_MAPPED		0x0001
 /* Located in metadata (could be copied from bd_inode) */
-#define EROFS_MAP_META		0x0002
-/* The extent is encoded */
-#define EROFS_MAP_ENCODED	0x0004
-/* The length of extent is full */
-#define EROFS_MAP_FULL_MAPPED	0x0008
+#define EROFS_MAP_META			0x0002
+/* @m_llen may be truncated by the runtime compared to the on-disk record */
+#define EROFS_MAP_PARTIAL_MAPPED	0x0004
+/* The on-disk @m_llen may cover only part of the encoded data */
+#define EROFS_MAP_PARTIAL_REF		0x0008
 /* Located in the special packed inode */
-#define __EROFS_MAP_FRAGMENT	0x0010
-/* The extent refers to partial decompressed data */
-#define EROFS_MAP_PARTIAL_REF	0x0020
-
-#define EROFS_MAP_FRAGMENT	(EROFS_MAP_MAPPED | __EROFS_MAP_FRAGMENT)
+#define EROFS_MAP_FRAGMENT		0x0010
+/* The encoded on-disk data will be fully handled (decompressed) */
+#define EROFS_MAP_FULL(f)	(!((f) & (EROFS_MAP_PARTIAL_MAPPED | \
+					  EROFS_MAP_PARTIAL_REF)))
 
 struct erofs_map_blocks {
 	struct erofs_buf buf;
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index b566996a0d1a..8a0b15511931 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -520,7 +520,7 @@ static bool z_erofs_should_alloc_cache(struct z_erofs_frontend *fe)
 	if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
 		return false;
 
-	if (!(fe->map.m_flags & EROFS_MAP_FULL_MAPPED))
+	if (fe->map.m_flags & EROFS_MAP_PARTIAL_MAPPED)
 		return true;
 
 	if (cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
@@ -1033,10 +1033,7 @@ static int z_erofs_scan_folio(struct z_erofs_frontend *f,
 		/* bump split parts first to avoid several separate cases */
 		++split;
 
-		if (!(map->m_flags & EROFS_MAP_MAPPED)) {
-			folio_zero_segment(folio, cur, end);
-			tight = false;
-		} else if (map->m_flags & __EROFS_MAP_FRAGMENT) {
+		if (map->m_flags & EROFS_MAP_FRAGMENT) {
 			erofs_off_t fpos = offset + cur - map->m_la;
 
 			err = z_erofs_read_fragment(inode->i_sb, folio, cur,
@@ -1045,6 +1042,9 @@ static int z_erofs_scan_folio(struct z_erofs_frontend *f,
 			if (err)
 				break;
 			tight = false;
+		} else if (!(map->m_flags & EROFS_MAP_MAPPED)) {
+			folio_zero_segment(folio, cur, end);
+			tight = false;
 		} else {
 			if (!f->pcl) {
 				err = z_erofs_pcluster_begin(f);
@@ -1080,14 +1080,13 @@ static int z_erofs_scan_folio(struct z_erofs_frontend *f,
 				f->pcl->length = offset + end - map->m_la;
 				f->pcl->pageofs_out = map->m_la & ~PAGE_MASK;
 			}
-			if ((map->m_flags & EROFS_MAP_FULL_MAPPED) &&
-			    !(map->m_flags & EROFS_MAP_PARTIAL_REF) &&
+			if (EROFS_MAP_FULL(map->m_flags) &&
 			    f->pcl->length == map->m_llen)
 				f->pcl->partial = false;
 		}
 		/* shorten the remaining extent to update progress */
 		map->m_llen = offset + cur - map->m_la;
-		map->m_flags &= ~EROFS_MAP_FULL_MAPPED;
+		map->m_flags |= EROFS_MAP_PARTIAL_MAPPED;
 		if (cur <= pgs) {
 			split = cur < pgs;
 			tight = (bs == PAGE_SIZE);
@@ -1841,7 +1840,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,
 		map->m_la = end;
 		err = z_erofs_map_blocks_iter(inode, map,
 					      EROFS_GET_BLOCKS_READMORE);
-		if (err || !(map->m_flags & EROFS_MAP_ENCODED))
+		if (err || !(map->m_flags & EROFS_MAP_MAPPED))
 			return;
 
 		/* expand ra for the trailing edge if readahead */
@@ -1853,7 +1852,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,
 		end = round_up(end, PAGE_SIZE);
 	} else {
 		end = round_up(map->m_la, PAGE_SIZE);
-		if (!(map->m_flags & EROFS_MAP_ENCODED) || !map->m_llen)
+		if (!(map->m_flags & EROFS_MAP_MAPPED) || !map->m_llen)
 			return;
 	}
 
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 30775502b56d..67f55b9b57af 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -419,7 +419,7 @@ static int z_erofs_map_blocks_fo(struct inode *inode,
 
 	if ((flags & EROFS_GET_BLOCKS_FINDTAIL) && ztailpacking)
 		vi->z_fragmentoff = m.nextpackoff;
-	map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_ENCODED;
+	map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_PARTIAL_MAPPED;
 	end = (m.lcn + 1ULL) << lclusterbits;
 
 	if (m.type != Z_EROFS_LCLUSTER_TYPE_NONHEAD && endoff >= m.clusterofs) {
@@ -435,7 +435,7 @@ static int z_erofs_map_blocks_fo(struct inode *inode,
 	} else {
 		if (m.type != Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
 			end = (m.lcn << lclusterbits) | m.clusterofs;
-			map->m_flags |= EROFS_MAP_FULL_MAPPED;
+			map->m_flags &= ~EROFS_MAP_PARTIAL_MAPPED;
 			m.delta[0] = 1;
 		}
 		/* get the corresponding first chunk */
@@ -496,7 +496,7 @@ static int z_erofs_map_blocks_fo(struct inode *inode,
 	      map->m_llen >= i_blocksize(inode))) {
 		err = z_erofs_get_extent_decompressedlen(&m);
 		if (!err)
-			map->m_flags |= EROFS_MAP_FULL_MAPPED;
+			map->m_flags &= ~EROFS_MAP_PARTIAL_MAPPED;
 	}
 
 unmap_out:
@@ -594,8 +594,7 @@ static int z_erofs_map_blocks_ext(struct inode *inode,
 			if (recsz > offsetof(struct z_erofs_extent, pstart_lo))
 				vi->z_fragmentoff |= map->m_pa << 32;
 		} else if (map->m_plen & Z_EROFS_EXTENT_PLEN_MASK) {
-			map->m_flags |= EROFS_MAP_MAPPED |
-				EROFS_MAP_FULL_MAPPED | EROFS_MAP_ENCODED;
+			map->m_flags |= EROFS_MAP_MAPPED;
 			fmt = map->m_plen >> Z_EROFS_EXTENT_PLEN_FMT_BIT;
 			if (map->m_plen & Z_EROFS_EXTENT_PLEN_PARTIAL)
 				map->m_flags |= EROFS_MAP_PARTIAL_REF;
@@ -714,7 +713,7 @@ static int z_erofs_map_sanity_check(struct inode *inode,
 	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
 	u64 pend;
 
-	if (!(map->m_flags & EROFS_MAP_ENCODED))
+	if (!(map->m_flags & EROFS_MAP_MAPPED))
 		return 0;
 	if (unlikely(map->m_algorithmformat >= Z_EROFS_COMPRESSION_RUNTIME_MAX)) {
 		erofs_err(inode->i_sb, "unknown algorithm %d @ pos %llu for nid %llu, please upgrade kernel",
@@ -781,10 +780,12 @@ static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
 	iomap->bdev = inode->i_sb->s_bdev;
 	iomap->offset = map.m_la;
 	iomap->length = map.m_llen;
-	if (map.m_flags & EROFS_MAP_MAPPED) {
+	if (map.m_flags & EROFS_MAP_FRAGMENT) {
 		iomap->type = IOMAP_MAPPED;
-		iomap->addr = map.m_flags & __EROFS_MAP_FRAGMENT ?
-			      IOMAP_NULL_ADDR : map.m_pa;
+		iomap->addr = IOMAP_NULL_ADDR;
+	} else if (map.m_flags & EROFS_MAP_MAPPED) {
+		iomap->type = IOMAP_MAPPED;
+		iomap->addr = map.m_pa;
 	} else {
 		iomap->type = IOMAP_HOLE;
 		iomap->addr = IOMAP_NULL_ADDR;
diff --git a/include/trace/events/erofs.h b/include/trace/events/erofs.h
index def20d06507b..cd0e3fd8c23f 100644
--- a/include/trace/events/erofs.h
+++ b/include/trace/events/erofs.h
@@ -26,10 +26,9 @@ struct erofs_map_blocks;
 #define show_mflags(flags) __print_flags(flags, "",	\
 	{ EROFS_MAP_MAPPED,		"M" },		\
 	{ EROFS_MAP_META,		"I" },		\
-	{ EROFS_MAP_ENCODED,		"E" },		\
-	{ EROFS_MAP_FULL_MAPPED,	"F" },		\
-	{ EROFS_MAP_FRAGMENT,		"R" },		\
-	{ EROFS_MAP_PARTIAL_REF,	"P" })
+	{ EROFS_MAP_PARTIAL_MAPPED,	"T" },		\
+	{ EROFS_MAP_PARTIAL_REF,	"P" },		\
+	{ EROFS_MAP_FRAGMENT,		"R" })
 
 TRACE_EVENT(erofs_lookup,
 
-- 
2.43.5