The issue of how to prevent a page from being modified as it is
written out (due to signing in our case) has been discussed on lkml a
few times (e.g. T10 block devices). We should hold off on changing
this until we have a way of handling the case of: we calculate the
signature, but just before the page in the cache is remodified, we
send it with the wrong signature ... obviously if we reissue the write
we are fine (the data is fine) but there may be better ways to lock
the page (and some suggestions have been made on lkml for similar
sounding problems).
On Tue, Dec 7, 2010 at 10:13 AM, Jeff Layton <jlayton@xxxxxxxxx> wrote:
> On Tue, 7 Dec 2010 09:23:55 -0500
> Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
>> This flag only affects a couple of places in the write codepath, and
>> it's not entirely clear to me what the purpose of it is. I've never
>> known anyone (even developers) to use this knob, so let's remove it.
>>
>> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>> ---
>> fs/cifs/cifs_debug.c | 42 ------------------------------------------
>> fs/cifs/cifsfs.c | 1 -
>> fs/cifs/cifsglob.h | 1 -
>> fs/cifs/file.c | 6 +++---
>> 4 files changed, 3 insertions(+), 47 deletions(-)
>>
>> diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
>> index 103ab8b..04eecb2 100644
>> --- a/fs/cifs/cifs_debug.c
>> +++ b/fs/cifs/cifs_debug.c
>> @@ -425,7 +425,6 @@ static const struct file_operations cifs_lookup_cache_proc_fops;
>> static const struct file_operations traceSMB_proc_fops;
>> static const struct file_operations cifs_multiuser_mount_proc_fops;
>> static const struct file_operations cifs_security_flags_proc_fops;
>> -static const struct file_operations cifs_experimental_proc_fops;
>> static const struct file_operations cifs_linux_ext_proc_fops;
>>
>> void
>> @@ -443,8 +442,6 @@ cifs_proc_init(void)
>> proc_create("cifsFYI", 0, proc_fs_cifs, &cifsFYI_proc_fops);
>> proc_create("traceSMB", 0, proc_fs_cifs, &traceSMB_proc_fops);
>> proc_create("OplockEnabled", 0, proc_fs_cifs, &cifs_oplock_proc_fops);
>> - proc_create("Experimental", 0, proc_fs_cifs,
>> - &cifs_experimental_proc_fops);
>> proc_create("LinuxExtensionsEnabled", 0, proc_fs_cifs,
>> &cifs_linux_ext_proc_fops);
>> proc_create("MultiuserMount", 0, proc_fs_cifs,
>> @@ -552,45 +549,6 @@ static const struct file_operations cifs_oplock_proc_fops = {
>> .write = cifs_oplock_proc_write,
>> };
>>
>> -static int cifs_experimental_proc_show(struct seq_file *m, void *v)
>> -{
>> - seq_printf(m, "%d\n", experimEnabled);
>> - return 0;
>> -}
>> -
>> -static int cifs_experimental_proc_open(struct inode *inode, struct file *file)
>> -{
>> - return single_open(file, cifs_experimental_proc_show, NULL);
>> -}
>> -
>> -static ssize_t cifs_experimental_proc_write(struct file *file,
>> - const char __user *buffer, size_t count, loff_t *ppos)
>> -{
>> - char c;
>> - int rc;
>> -
>> - rc = get_user(c, buffer);
>> - if (rc)
>> - return rc;
>> - if (c == '0' || c == 'n' || c == 'N')
>> - experimEnabled = 0;
>> - else if (c == '1' || c == 'y' || c == 'Y')
>> - experimEnabled = 1;
>> - else if (c == '2')
>> - experimEnabled = 2;
>> -
>> - return count;
>> -}
>> -
>> -static const struct file_operations cifs_experimental_proc_fops = {
>> - .owner = THIS_MODULE,
>> - .open = cifs_experimental_proc_open,
>> - .read = seq_read,
>> - .llseek = seq_lseek,
>> - .release = single_release,
>> - .write = cifs_experimental_proc_write,
>> -};
>> -
>> static int cifs_linux_ext_proc_show(struct seq_file *m, void *v)
>> {
>> seq_printf(m, "%d\n", linuxExtEnabled);
>> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
>> index 48582b7..932a347 100644
>> --- a/fs/cifs/cifsfs.c
>> +++ b/fs/cifs/cifsfs.c
>> @@ -53,7 +53,6 @@ int cifsFYI = 0;
>> int cifsERROR = 1;
>> int traceSMB = 0;
>> unsigned int oplockEnabled = 1;
>> -unsigned int experimEnabled = 0;
>> unsigned int linuxExtEnabled = 1;
>> unsigned int lookupCacheEnabled = 1;
>> unsigned int multiuser_mount = 0;
>> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
>> index 37fb246..5ab6701 100644
>> --- a/fs/cifs/cifsglob.h
>> +++ b/fs/cifs/cifsglob.h
>> @@ -777,7 +777,6 @@ GLOBAL_EXTERN unsigned int multiuser_mount; /* if enabled allows new sessions
>> have the uid/password or Kerberos credential
>> or equivalent for current user */
>> GLOBAL_EXTERN unsigned int oplockEnabled;
>> -GLOBAL_EXTERN unsigned int experimEnabled;
>> GLOBAL_EXTERN unsigned int lookupCacheEnabled;
>> GLOBAL_EXTERN unsigned int global_secflags; /* if on, session setup sent
>> with more secure ntlmssp2 challenge/resp */
>> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>> index 5a28660..5f6907e 100644
>> --- a/fs/cifs/file.c
>> +++ b/fs/cifs/file.c
>> @@ -1054,10 +1054,10 @@ static ssize_t cifs_write(struct cifsFileInfo *open_file,
>> if (rc != 0)
>> break;
>> }
>> - if (experimEnabled || (pTcon->ses->server &&
>> + if (pTcon->ses->server &&
>> ((pTcon->ses->server->secMode &
>> (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED))
>> - == 0))) {
>> + == 0)) {
>> struct kvec iov[2];
>> unsigned int len;
>>
>> @@ -1319,7 +1319,7 @@ static int cifs_writepages(struct address_space *mapping,
>> }
>>
>> tcon = tlink_tcon(open_file->tlink);
>> - if (!experimEnabled && tcon->ses->server->secMode &
>> + if (tcon->ses->server->secMode &
>> (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
>> cifsFileInfo_put(open_file);
>> kfree(iov);
>
> Just noticed that this misses removing the de-registration of
> "Experimental", so it'll need to be respun.
>
> --
> Jeff Layton <jlayton@xxxxxxxxx>
>
--
Thanks,
Steve
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