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ovl: fix corner case of non-unique st_dev;st_ino
commit9c6d8f13e9
upstream. On non-samefs overlay without xino, non pure upper inodes should use a pseudo_dev assigned to each unique lower fs and pure upper inodes use the real upper st_dev. It is fine for an overlay pure upper inode to use the same st_dev;st_ino values as the real upper inode, because the content of those two different filesystem objects is always the same. In this case, however: - two filesystems, A and B - upper layer is on A - lower layer 1 is also on A - lower layer 2 is on B Non pure upper overlay inode, whose origin is in layer 1 will have the same st_dev;st_ino values as the real lower inode. This may result with a false positive results of 'diff' between the real lower and copied up overlay inode. Fix this by using the upper st_dev;st_ino values in this case. This breaks the property of constant st_dev;st_ino across copy up of this case. This breakage will be fixed by a later patch. Fixes:5148626b80
("ovl: allocate anon bdev per unique lower fs") Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 7 additions and 1 deletions
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@ -200,8 +200,14 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
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if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
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if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
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(!ovl_verify_lower(dentry->d_sb) &&
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(!ovl_verify_lower(dentry->d_sb) &&
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(is_dir || lowerstat.nlink == 1))) {
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(is_dir || lowerstat.nlink == 1))) {
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stat->ino = lowerstat.ino;
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lower_layer = ovl_layer_lower(dentry);
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lower_layer = ovl_layer_lower(dentry);
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/*
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* Cannot use origin st_dev;st_ino because
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* origin inode content may differ from overlay
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* inode content.
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*/
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if (samefs || lower_layer->fsid)
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stat->ino = lowerstat.ino;
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}
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}
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/*
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/*
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