erofs: address D-cache aliasing

Flush the D-cache before unlocking folios for compressed inodes, as
they are dirtied during decompression.

Avoid calling flush_dcache_folio() on every CPU write, since it's more
like playing whack-a-mole without real benefit.

It has no impact on x86 and arm64/risc-v: on x86, flush_dcache_folio()
is a no-op, and on arm64/risc-v, PG_dcache_clean (PG_arch_1) is clear
for new page cache folios.  However, certain ARM boards are affected,
as reported.

Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
Closes: https://lore.kernel.org/r/c1e51e16-6cc6-49d0-a63e-4e9ff6c4dd53@pengutronix.de
Closes: https://lore.kernel.org/r/38d43fae-1182-4155-9c5b-ffc7382d9917@siemens.com
Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
Tested-by: Stefan Kerkmann <s.kerkmann@pengutronix.de>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250709034614.2780117-2-hsiangkao@linux.alibaba.com

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 221e0ff1ed0d52cc785716837b78c40bacfbc794..16e4a6bd9b9737a1581416957b9e16ced97d9c91 100644 (file)
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -214,9 +214,11 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 
 /*
  * bit 30: I/O error occurred on this folio
+ * bit 29: CPU has dirty data in D-cache (needs aliasing handling);
  * bit 0 - 29: remaining parts to complete this folio
  */
-#define EROFS_ONLINEFOLIO_EIO                  (1 << 30)
+#define EROFS_ONLINEFOLIO_EIO          30
+#define EROFS_ONLINEFOLIO_DIRTY                29
 
 void erofs_onlinefolio_init(struct folio *folio)
 {
@@ -233,19 +235,23 @@ void erofs_onlinefolio_split(struct folio *folio)
        atomic_inc((atomic_t *)&folio->private);
 }
 
-void erofs_onlinefolio_end(struct folio *folio, int err)
+void erofs_onlinefolio_end(struct folio *folio, int err, bool dirty)
 {
        int orig, v;
 
        do {
                orig = atomic_read((atomic_t *)&folio->private);
-               v = (orig - 1) | (err ? EROFS_ONLINEFOLIO_EIO : 0);
+               DBG_BUGON(orig <= 0);
+               v = dirty << EROFS_ONLINEFOLIO_DIRTY;
+               v |= (orig - 1) | (!!err << EROFS_ONLINEFOLIO_EIO);
        } while (atomic_cmpxchg((atomic_t *)&folio->private, orig, v) != orig);
 
-       if (v & ~EROFS_ONLINEFOLIO_EIO)
+       if (v & (BIT(EROFS_ONLINEFOLIO_DIRTY) - 1))
                return;
        folio->private = 0;
-       folio_end_read(folio, !(v & EROFS_ONLINEFOLIO_EIO));
+       if (v & BIT(EROFS_ONLINEFOLIO_DIRTY))
+               flush_dcache_folio(folio);
+       folio_end_read(folio, !(v & BIT(EROFS_ONLINEFOLIO_EIO)));
 }
 
 static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index bf62e2836b604cc21b2bf61fa131e16a84e46977..358061d7b660744c6d518a381fa36992618c175d 100644 (file)
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -301,13 +301,11 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
                cur = min(cur, rq->outputsize);
                if (cur && rq->out[0]) {
                        kin = kmap_local_page(rq->in[nrpages_in - 1]);
-                       if (rq->out[0] == rq->in[nrpages_in - 1]) {
+                       if (rq->out[0] == rq->in[nrpages_in - 1])
                                memmove(kin + rq->pageofs_out, kin + pi, cur);
-                               flush_dcache_page(rq->out[0]);
-                       } else {
+                       else
                                memcpy_to_page(rq->out[0], rq->pageofs_out,
                                               kin + pi, cur);
-                       }
                        kunmap_local(kin);
                }
                rq->outputsize -= cur;
@@ -325,14 +323,12 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
                        po = (rq->pageofs_out + cur + pi) & ~PAGE_MASK;
                        DBG_BUGON(no >= nrpages_out);
                        cnt = min(insz - pi, PAGE_SIZE - po);
-                       if (rq->out[no] == rq->in[ni]) {
+                       if (rq->out[no] == rq->in[ni])
                                memmove(kin + po,
                                        kin + rq->pageofs_in + pi, cnt);
-                               flush_dcache_page(rq->out[no]);
-                       } else if (rq->out[no]) {
+                       else if (rq->out[no])
                                memcpy_to_page(rq->out[no], po,
                                               kin + rq->pageofs_in + pi, cnt);
-                       }
                        pi += cnt;
                } while (pi < insz);
                kunmap_local(kin);

diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
index fe2cd2982b4b9cd4fd428c769f27867c88beeecd..91781718199e2a1c668da20c206491e534b9a9b7 100644 (file)
--- a/fs/erofs/fileio.c
+++ b/fs/erofs/fileio.c
@@ -38,7 +38,7 @@ static void erofs_fileio_ki_complete(struct kiocb *iocb, long ret)
        } else {
                bio_for_each_folio_all(fi, &rq->bio) {
                        DBG_BUGON(folio_test_uptodate(fi.folio));
-                       erofs_onlinefolio_end(fi.folio, ret);
+                       erofs_onlinefolio_end(fi.folio, ret, false);
                }
        }
        bio_uninit(&rq->bio);
@@ -154,7 +154,7 @@ io_retry:
                }
                cur += len;
        }
-       erofs_onlinefolio_end(folio, err);
+       erofs_onlinefolio_end(folio, err, false);
        return err;
 }
 

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index a32c03a80c7001c73833ff6cd33c297320ffa61d..0d19bde8c09421abc8109a2fbaec23741fcf98dc 100644 (file)
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -390,7 +390,7 @@ int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 int erofs_map_blocks(struct inode *inode, struct erofs_map_blocks *map);
 void erofs_onlinefolio_init(struct folio *folio);
 void erofs_onlinefolio_split(struct folio *folio);
-void erofs_onlinefolio_end(struct folio *folio, int err);
+void erofs_onlinefolio_end(struct folio *folio, int err, bool dirty);
 struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid);
 int erofs_getattr(struct mnt_idmap *idmap, const struct path *path,
                  struct kstat *stat, u32 request_mask,

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index fe80718447247d61d2092914a592b13e35706b9f..32e3905e75fefcd92b5548b34a49ca1d8376ebd8 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1091,7 +1091,7 @@ static int z_erofs_scan_folio(struct z_erofs_frontend *f,
                        tight = (bs == PAGE_SIZE);
                }
        } while ((end = cur) > 0);
-       erofs_onlinefolio_end(folio, err);
+       erofs_onlinefolio_end(folio, err, false);
        return err;
 }
 
@@ -1196,7 +1196,7 @@ static void z_erofs_fill_other_copies(struct z_erofs_backend *be, int err)
                        cur += len;
                }
                kunmap_local(dst);
-               erofs_onlinefolio_end(page_folio(bvi->bvec.page), err);
+               erofs_onlinefolio_end(page_folio(bvi->bvec.page), err, true);
                list_del(p);
                kfree(bvi);
        }
@@ -1355,7 +1355,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_backend *be, int err)
 
                DBG_BUGON(z_erofs_page_is_invalidated(page));
                if (!z_erofs_is_shortlived_page(page)) {
-                       erofs_onlinefolio_end(page_folio(page), err);
+                       erofs_onlinefolio_end(page_folio(page), err, true);
                        continue;
                }
                if (pcl->algorithmformat != Z_EROFS_COMPRESSION_LZ4) {