On Sun, Sep 16, 2012 at 08:23:20AM -0400, Namjae Jeon wrote:
> From: Namjae Jeon <namjae.j...@samsung.com>
>
> update nfs option in filesystem/vfat.txt
>
> Signed-off-by: Namjae Jeon <namjae.j...@samsung.com>
> Signed-off-by: Ravishankar N <ravi...@samsung.com>
> Signed-off-by: Amit Sahrawat <a.sahra...@samsung.com>
> ---
> Documentation/filesystems/vfat.txt | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/filesystems/vfat.txt
> b/Documentation/filesystems/vfat.txt
> index de1e6c4..3371b8e 100644
> --- a/Documentation/filesystems/vfat.txt
> +++ b/Documentation/filesystems/vfat.txt
> @@ -141,13 +141,22 @@ discard -- If set, issues discard/TRIM commands
> to the block
> device when blocks are freed. This is useful for SSD devices
> and sparse/thinly-provisoned LUNs.
>
> -nfs -- This option maintains an index (cache) of directory
> - inodes by i_logstart which is used by the nfs-related code to
> - improve look-ups.
> -
> - Enable this only if you want to export the FAT filesystem
> +nfs=full_unstable|limited_stable
You still want to accept just "nfs" (defaulting to "full_unstable"
behavior), for backwards compatibility.
Also I don't find this full_unstable/limited_stable terminology very
intuitive. "stable" and "limited" could mean too many different things.
Maybe "nostale_ro|stale_rw" ?
> + -- Enable this only if you want to export the FAT filesystem
> over NFS
>
> + full_unstable:This option maintains an index (cache) of
> + directory inodes by i_logstart which is used by
> + the nfs-related code to improve look-ups.Full file operations
> + (read/write) over NFS is supported but with cache eviction
> + at NFS server, this could result in ESTALE issues.
> +
> + limited_stable:This options makes NFS support for FAT as
> + read-only and provides stable inode based on the on-disk
> + location of the MS-DOS directory entry.This helps in
> + reconstruction of the inodes in case of lookup failure,
> + making FAT behaviour stable with respect to ESTALE issues.
This option still scares me a little. Maybe a little more explanation:
This option bases the inode number and filehandle on
the location of an file in the MS-DOS directory entry.
This ensures that ESTALE will not be returned after a
file is evicted from the inode cache. However, it means
that operations such as rename, create, and unlink could
cause filehandles that previously pointed at one file to
point at a different file, potentially causing data
corruption. For this reason, this option also mounts
the filesystem readonly.
--b.
> +
> <bool>: 0,1,yes,no,true,false
>
> TODO
> --
> 1.7.9.5
>
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