linux-kernel - Re: [PATCH] staging: exfat: add millisecond support

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Message-ID: <20190908144735.GA7664@valentin-vidic.from.hr>
Date:   Sun, 8 Sep 2019 14:47:35 +0000
From:   Valentin Vidić <vvidic@...entin-vidic.from.hr>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     devel@...verdev.osuosl.org,
        Valdis Kletnieks <valdis.kletnieks@...edu>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: exfat: add millisecond support

On Sun, Sep 08, 2019 at 02:03:37PM +0100, Greg Kroah-Hartman wrote:
> Please run checkpatch on your patches so that we don't have to go and
> fix up those issues later on.

Strange, it did not report anything for me:

total: 0 errors, 0 warnings, 0 checks, 439 lines checked
0001-staging-exfat-add-millisecond-support.patch has no obvious style problems and is ready for submission.

> Also, can you break this up into smaller patches please?  You are doing
> multiple things all at once.

Sure, I was just trying to improve the code a bit :)

> And, are you sure about the millisecond field for access time stuff?  It
> was obviously added for some reason (there are lots in the spec that the
> code does not yet cover, this seems odd being the other way around).
> Did you test it against any other operating system exfat images to
> ensure that it really is not being used at all?  If so, which ones?

Don't really have access to another OS, but here is what exfat-fuse has:

struct exfat_entry_meta1                        /* file or directory info (part 1) */
{
        uint8_t type;                                   /* EXFAT_ENTRY_FILE */
        uint8_t continuations;
        le16_t checksum;
        le16_t attrib;                                  /* combination of EXFAT_ATTRIB_xxx */
        le16_t __unknown1;
        le16_t crtime, crdate;                  /* creation date and time */
        le16_t mtime, mdate;                    /* latest modification date and time */
        le16_t atime, adate;                    /* latest access date and time */
        uint8_t crtime_cs;                              /* creation time in cs (centiseconds) */
        uint8_t mtime_cs;                               /* latest modification time in cs */
        uint8_t __unknown2[10];
}

The spec matches this and defines 3 additional UtcOffset fields that we don't use:

EntryType
SecondaryCount
SetChecksum
FileAttributes
Reserved1
CreateTimestamp
LastModifiedTimestamp
LastAccessedTimestamp
Create10msIncrement
LastModified10msIncrement

CreateUtcOffset (1 byte)
LastModifiedUtcOffset (1 byte)
LastAccessedUtcOffset (1 byte)
Reserved2 (7 bytes)

So I'm not sure where access_time_ms came from. In any case it was always set to
0 so it should not matter much?

-- 
Valentin