On 2024/3/6 13:31, Gao Xiang wrote:
There are mainly two reasons that thp_get_unmapped_area() should be
used for EROFS as other filesystems:

  - It's needed to enable PMD mappings as a FSDAX filesystem, see
    commit 74d2fad1334d ("thp, dax: add thp_get_unmapped_area for pmd
    mappings");

  - It's useful together with CONFIG_READ_ONLY_THP_FOR_FS which enables
    THPs for read-only mmapped files (e.g. shared libraries) even without
    FSDAX.  See commit 1854bc6e2420 ("mm/readahead: Align file mappings
    for non-DAX").

Refine this part as

 - It's useful together with large folios and CONFIG_READ_ONLY_THP_FOR_FS
   which enable THPs for mmapped files (e.g. shared libraries) even without
   ...


Fixes: 06252e9ce05b ("erofs: dax support for non-tailpacking regular file")

Fixes: ce529cc25b18 ("erofs: enable large folios for iomap mode")
Fixes: be62c5198861 ("erofs: enable large folios for fscache mode")

Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
---
  fs/erofs/data.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index c98aeda8abb2..3d9721b3faa8 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -447,5 +447,6 @@ const struct file_operations erofs_file_fops = {
        .llseek         = generic_file_llseek,
        .read_iter      = erofs_file_read_iter,
        .mmap           = erofs_file_mmap,
+       .get_unmapped_area = thp_get_unmapped_area,
        .splice_read    = filemap_splice_read,
  };

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