2011/4/10 Jeff Layton <jlayton@xxxxxxxxxx>:
> On Sun, 10 Apr 2011 14:05:54 +0400
> Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
>
>> Add cifs_match_super to use in sget to share superblock between mounts
>> that have the same //server/sharename, credentials and mount options.
>> It helps us to improve performance on work with future SMB2.1 leases.
>>
>> Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
>> ---
>> fs/cifs/cifsfs.c | 6 ++-
>> fs/cifs/connect.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 97 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
>> index c40c1f4..abc8436 100644
>> --- a/fs/cifs/cifsfs.c
>> +++ b/fs/cifs/cifsfs.c
>> @@ -577,14 +577,16 @@ cifs_do_mount(struct file_system_type *fs_type,
>> if (rc)
>> return ERR_PTR(rc);
>>
>> - sb = sget(fs_type, NULL, set_anon_super, NULL);
>> + sb = sget(fs_type, cifs_match_super, set_anon_super, volume_info);
>> if (IS_ERR(sb)) {
>> cifs_cleanup_volume_info(&volume_info);
>> return ERR_CAST(sb);
>> }
>>
>> - if (sb->s_fs_info)
>> + if (sb->s_fs_info) {
>> + cFYI(1, "Use existing superblock");
>> goto out;
>> + }
>>
>> sb->s_flags = flags;
>>
>> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
>> index 53b79e7..7c98c36 100644
>> --- a/fs/cifs/connect.c
>> +++ b/fs/cifs/connect.c
>> @@ -2193,6 +2193,99 @@ cifs_put_tlink(struct tcon_link *tlink)
>> return;
>> }
>>
>> +static void setup_cifs_sb(struct smb_vol *vol, struct cifs_sb_info *sb);
>> +static inline struct tcon_link *
>> +cifs_sb_master_tlink(struct cifs_sb_info *cifs_sb);
>> +
>> +static const u32 ACTUAL_MOUNT_FLAGS = CIFS_MOUNT_NO_PERM | CIFS_MOUNT_SET_UID |
>> + CIFS_MOUNT_SERVER_INUM | CIFS_MOUNT_DIRECT_IO | CIFS_MOUNT_NO_XATTR |
>> + CIFS_MOUNT_MAP_SPECIAL_CHR | CIFS_MOUNT_UNX_EMUL | CIFS_MOUNT_NO_BRL |
>> + CIFS_MOUNT_CIFS_ACL | CIFS_MOUNT_OVERR_UID | CIFS_MOUNT_OVERR_GID |
>> + CIFS_MOUNT_DYNPERM | CIFS_MOUNT_NOPOSIXBRL | CIFS_MOUNT_NOSSYNC |
>> + CIFS_MOUNT_FSCACHE | CIFS_MOUNT_MF_SYMLINKS | CIFS_MOUNT_MULTIUSER |
>> + CIFS_MOUNT_STRICT_IO;
>> +
>> +static int
>> +compare_mount_options(struct super_block *sb, struct smb_vol *vol)
>> +{
>> + struct cifs_sb_info *old = CIFS_SB(sb), new;
>> +
>> + setup_cifs_sb(vol, &new);
>> +
>> + if ((old->mnt_cifs_flags & ACTUAL_MOUNT_FLAGS) !=
>> + (new.mnt_cifs_flags & ACTUAL_MOUNT_FLAGS))
>> + return 0;
>> +
>> + if (old->rsize != new.rsize || old->wsize != new.wsize)
>> + return 0;
>> +
>> + if (old->mnt_uid != new.mnt_uid || old->mnt_gid != new.mnt_gid)
>> + return 0;
>> +
>> + if (old->mnt_file_mode != new.mnt_file_mode ||
>> + old->mnt_dir_mode != new.mnt_dir_mode)
>> + return 0;
>> +
>> + if (old->prepathlen != new.prepathlen ||
>> + strncmp(old->prepath, new.prepath, old->prepathlen))
>> + return 0;
>> +
>
> I don't think this is really what you want...
>
> Suppose I mount the same share twice, but with 2 different prepaths.
> For instance:
>
> //server/share/foo
>
> ...and...
>
> //server/share/foo/bar
>
> ...shouldn't the inodes for files/directories accessable via both
> mounts be shared in that case?
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
> --
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>
I understand that sharing superblock in your case is a good idea, but
it can be another task, I think, - we can always add this capability
later.
Now I suggest to discuss mount option list - are you agree with it? or
we can drop/add something?
--
Best regards,
Pavel Shilovsky.
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