erofs: fix large fragment handling

Fragments aren't limited by Z_EROFS_PCLUSTER_MAX_DSIZE. However, if
a fragment's logical length is larger than Z_EROFS_PCLUSTER_MAX_DSIZE
but the fragment is not the whole inode, it currently returns
-EOPNOTSUPP because m_flags has the wrong EROFS_MAP_ENCODED flag set.
It is not intended by design but should be rare, as it can only be
reproduced by mkfs with `-Eall-fragments` in a specific case.

Let's normalize fragment m_flags using the new EROFS_MAP_FRAGMENT.

Reported-by: Axel Fontaine <axel@axelfontaine.com>
Closes: https://github.com/erofs/erofs-utils/issues/23
Fixes: 7c3ca1838a78 ("erofs: restrict pcluster size limitations")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250711195826.3601157-1-hsiangkao@linux.alibaba.com

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 0d19bde8c09421abc8109a2fbaec23741fcf98dc..06b867d2fc3b7ccf36c9fb135baa877e0d5b6d63 100644 (file)
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -315,10 +315,12 @@ static inline struct folio *erofs_grab_folio_nowait(struct address_space *as,
 /* The length of extent is full */
 #define EROFS_MAP_FULL_MAPPED  0x0008
 /* Located in the special packed inode */
-#define EROFS_MAP_FRAGMENT     0x0010
+#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)
+
 struct erofs_map_blocks {
        struct erofs_buf buf;
 

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 32e3905e75fefcd92b5548b34a49ca1d8376ebd8..e3f28a1bb9452e4d65ad80f3ee479ad1d06c9bf8 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1034,7 +1034,7 @@ static int z_erofs_scan_folio(struct z_erofs_frontend *f,
                if (!(map->m_flags & EROFS_MAP_MAPPED)) {
                        folio_zero_segment(folio, cur, end);
                        tight = false;
-               } else if (map->m_flags & EROFS_MAP_FRAGMENT) {
+               } else 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,

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 0bebc6e3a4d7dd8d1c25826951df7113fcf5d332..f1a15ff22147ba1bfff0ac4203d17d8c93a57136 100644 (file)
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -413,8 +413,7 @@ static int z_erofs_map_blocks_fo(struct inode *inode,
            !vi->z_tailextent_headlcn) {
                map->m_la = 0;
                map->m_llen = inode->i_size;
-               map->m_flags = EROFS_MAP_MAPPED |
-                       EROFS_MAP_FULL_MAPPED | EROFS_MAP_FRAGMENT;
+               map->m_flags = EROFS_MAP_FRAGMENT;
                return 0;
        }
        initial_lcn = ofs >> lclusterbits;
@@ -489,7 +488,7 @@ static int z_erofs_map_blocks_fo(struct inode *inode,
                        goto unmap_out;
                }
        } else if (fragment && m.lcn == vi->z_tailextent_headlcn) {
-               map->m_flags |= EROFS_MAP_FRAGMENT;
+               map->m_flags = EROFS_MAP_FRAGMENT;
        } else {
                map->m_pa = erofs_pos(sb, m.pblk);
                err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
@@ -617,7 +616,7 @@ static int z_erofs_map_blocks_ext(struct inode *inode,
        if (lstart < lend) {
                map->m_la = lstart;
                if (last && (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER)) {
-                       map->m_flags |= EROFS_MAP_MAPPED | EROFS_MAP_FRAGMENT;
+                       map->m_flags = EROFS_MAP_FRAGMENT;
                        vi->z_fragmentoff = map->m_plen;
                        if (recsz > offsetof(struct z_erofs_extent, pstart_lo))
                                vi->z_fragmentoff |= map->m_pa << 32;
@@ -797,7 +796,7 @@ static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
        iomap->length = map.m_llen;
        if (map.m_flags & EROFS_MAP_MAPPED) {
                iomap->type = IOMAP_MAPPED;
-               iomap->addr = map.m_flags & EROFS_MAP_FRAGMENT ?
+               iomap->addr = map.m_flags & __EROFS_MAP_FRAGMENT ?
                              IOMAP_NULL_ADDR : map.m_pa;
        } else {
                iomap->type = IOMAP_HOLE;