2011/5/25 Jeff Layton <jlayton@xxxxxxxxxx>:
> On Wed, 25 May 2011 23:10:33 +0400
> Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
>
>> 2011/5/24 Jeff Layton <jlayton@xxxxxxxxxx>:
>> > On Thu, 5 May 2011 13:55:14 +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 | 18 ++++++++++-
>> >> fs/cifs/cifsglob.h | 5 +++
>> >> fs/cifs/connect.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>> >> 3 files changed, 112 insertions(+), 1 deletions(-)
>> >>
>> >> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
>> >> index 446b5c2..ba0b7ae 100644
>> >> --- a/fs/cifs/cifsfs.c
>> >> +++ b/fs/cifs/cifsfs.c
>> >> @@ -644,6 +644,7 @@ cifs_do_mount(struct file_system_type *fs_type,
>> >> struct super_block *sb;
>> >> struct cifs_sb_info *cifs_sb;
>> >> struct smb_vol *volume_info;
>> >> + struct cifs_mnt_data mnt_data;
>> >> struct dentry *root;
>> >> char *copied_data = NULL;
>> >>
>> >> @@ -661,13 +662,21 @@ cifs_do_mount(struct file_system_type *fs_type,
>> >>
>> >> cifs_setup_cifs_sb(volume_info, cifs_sb);
>> >>
>> >> - sb = sget(fs_type, NULL, set_anon_super, NULL);
>> >> + mnt_data.vol = volume_info;
>> >> + mnt_data.cifs_sb = cifs_sb;
>> >> +
>> >> + sb = sget(fs_type, cifs_match_super, set_anon_super, &mnt_data);
>> >> if (IS_ERR(sb)) {
>> >> kfree(cifs_sb);
>> >> root = ERR_CAST(sb);
>> >> goto out;
>> >> }
>> >>
>> >> + if (sb->s_fs_info) {
>> >> + cFYI(1, "Use existing superblock");
>> >> + goto out_shared;
>> >> + }
>> >> +
>> >> sb->s_flags = flags;
>> >>
>> >> /*
>> >> @@ -700,6 +709,13 @@ out:
>> >> cifs_cleanup_volume_info(&volume_info);
>> >> return root;
>> >>
>> >> +out_shared:
>> >> + root = cifs_get_root(volume_info, sb);
>> >> + if (root)
>> >> + cFYI(1, "dentry root is: %p", root);
>> >> + cifs_cleanup_volume_info(&volume_info);
>> >> + return root;
>> >> +
>> >> err_out:
>> >> kfree(cifs_sb);
>> >> deactivate_locked_super(sb);
>> >> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
>> >> index 7ad7d69..55901b0 100644
>> >> --- a/fs/cifs/cifsglob.h
>> >> +++ b/fs/cifs/cifsglob.h
>> >> @@ -211,6 +211,11 @@ struct smb_vol {
>> >> struct nls_table *local_nls;
>> >> };
>> >>
>> >> +struct cifs_mnt_data {
>> >> + struct cifs_sb_info *cifs_sb;
>> >> + struct smb_vol *vol;
>> >> +};
>> >> +
>> >> struct TCP_Server_Info {
>> >> struct list_head tcp_ses_list;
>> >> struct list_head smb_ses_list;
>> >> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
>> >> index 1cacfaa..1d39dcf 100644
>> >> --- a/fs/cifs/connect.c
>> >> +++ b/fs/cifs/connect.c
>> >> @@ -2135,6 +2135,96 @@ cifs_put_tlink(struct tcon_link *tlink)
>> >> return;
>> >> }
>> >>
>> >> +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 cifs_sb_info *old, struct cifs_sb_info *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;
>> >> +
>> > ^^^^^^^^^^
>> > The rsize and wsize are negotiated -- you can't know what this is until
>> > you talk to the server. Doesn't this check always fail?
>>
>> If we don't specify wsize and rsize they are set to default values
>> (16384 and 57344) in both mounts, this check succeed.
>>
>
> Ahh then this will likely be broken if/when the wsize negotiation patch
> goes in. I suppose we'll have to see which patch (if any) Steve decides
> to commit first and then try to fix this up afterward.
>
> The brokenness shouldn't be too bad, you just won't be able to actually
> share superblocks until it's fixed.
>
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
>
Updated patch 4/4 with wsize changes and posted to the list.
--
Best regards,
Pavel Shilovsky.
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