readdir: require opt-in for d_type flags

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Commit c31f91c6af ("fuse: don't allow signals to interrupt getdents
copying") introduced the use of high bits in d_type as flags. However,
overlayfs was not adapted to handle this change.

In ovl_cache_entry_new(), the code checks if d_type == DT_CHR to
determine if an entry might be a whiteout. When fuse is used as the
lower layer and sets high bits in d_type, this comparison fails,
causing whiteout files to not be recognized properly and resulting in
incorrect overlayfs behavior.

Fix this by requiring callers of iterate_dir() to opt-in for getting
flag bits in d_type outside of S_DT_MASK.

Fixes: c31f91c6af ("fuse: don't allow signals to interrupt getdents copying")
Link: https://lore.kernel.org/all/20260107034551.439-1-luochunsheng@ustc.edu/
Link: https://github.com/containerd/stargz-snapshotter/issues/2214
Reported-by: Chunsheng Luo <luochunsheng@ustc.edu>
Reviewed-by: Chunsheng Luo <luochunsheng@ustc.edu>
Tested-by: Chunsheng Luo <luochunsheng@ustc.edu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20260108074522.3400998-1-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

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Amir Goldstein 2026-01-08 08:45:22 +01:00 • committed by Christian Brauner

parent 7d42f2b1cc

commit c644bce62b

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2 changed files with 8 additions and 1 deletions

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3

fs/readdir.c

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6

include/linux/fs.h

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