linux-ext4 - 回复: [f2fs-dev] [PATCH 1/2] ext4: only set project inherit bit for directory

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Message-ID: <MN2PR19MB3167ED3E8C9C85AE510F7BF4D4100@MN2PR19MB3167.namprd19.prod.outlook.com>
Date:   Fri, 7 Jun 2019 07:51:18 +0000
From:   Wang Shilong <wshilong@....com>
To:     Eric Biggers <ebiggers@...nel.org>,
        Wang Shilong <wangshilong1991@...il.com>
CC:     "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        "linux-f2fs-devel@...ts.sourceforge.net" 
        <linux-f2fs-devel@...ts.sourceforge.net>,
        Andreas Dilger <adilger@...ger.ca>
Subject: 回复: [f2fs-dev] [PATCH 1/2] ext4: only set project inherit bit for directory

Hi,

> --
> 2.21.0

Won't this break 'chattr' on files that already have this flag set?
FS_IOC_GETFLAGS will return this flag, so 'chattr' will pass it back to
FS_IOC_SETFLAGS which will return EOPNOTSUPP due to this:

        if (ext4_mask_flags(inode->i_mode, flags) != flags)
                return -EOPNOTSUPP;

>>>>

You are right for this and we also need take care of this in EXT4_IOC_FSSETXATTR/
this is a bit strange behavior as chattr read existed flags
but could not set them again, there are several possible ways that I could think
of to fix the issue?

1) change chattr to filter Project inherit bit before call FS_IOC_SETFLAGS

2) we automatically fixed the flag before mask check, something like:
if reg:
     flags &= ~PROJECT_INHERT;
      if (ext4_mask_flags(inode->i_mode, flags) != flags)
                return -EOPNOTSUPP;
But this might be not good..

I would prefer solution 1)
What do you think?