2010/11/9 Jeff Layton <jlayton@xxxxxxxxxxxxxxx>:
> On Fri, 5 Nov 2010 11:29:32 +0300
> Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
>
>> On strict cache mode when we close the last file handle of the inode we
>> should invalidate it to prevent data coherency problem when we open it
>> again but it has been modified by other clients.
>>
>> Signed-off-by: Pavel Shilovsky <piastryyy@xxxxxxxxx>
>> ---
>> fs/cifs/cifs_fs_sb.h | 1 +
>> fs/cifs/file.c | 6 ++++++
>> 2 files changed, 7 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
>> index e9a393c..be7b159 100644
>> --- a/fs/cifs/cifs_fs_sb.h
>> +++ b/fs/cifs/cifs_fs_sb.h
>> @@ -40,6 +40,7 @@
>> #define CIFS_MOUNT_FSCACHE 0x8000 /* local caching enabled */
>> #define CIFS_MOUNT_MF_SYMLINKS 0x10000 /* Minshall+French Symlinks enabled */
>> #define CIFS_MOUNT_MULTIUSER 0x20000 /* multiuser mount */
>> +#define CIFS_MOUNT_STRICT_IO 0x40000 /* strict cache mode */
>>
>> struct cifs_sb_info {
>> struct rb_root tlink_tree;
>> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>> index 777e7f4..b36de2e 100644
>> --- a/fs/cifs/file.c
>> +++ b/fs/cifs/file.c
>> @@ -264,7 +264,9 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
>> struct inode *inode = cifs_file->dentry->d_inode;
>> struct cifsTconInfo *tcon = tlink_tcon(cifs_file->tlink);
>> struct cifsInodeInfo *cifsi = CIFS_I(inode);
>> + struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
>> struct cifsLockInfo *li, *tmp;
>> + bool last_open_file = false;
>>
>> spin_lock(&cifs_file_list_lock);
>> if (--cifs_file->count > 0) {
>> @@ -279,10 +281,14 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
>> if (list_empty(&cifsi->openFileList)) {
>> cFYI(1, "closing last open instance for inode %p",
>> cifs_file->dentry->d_inode);
>> + last_open_file = true;
>> cifs_set_oplock_level(inode, 0);
>> }
>> spin_unlock(&cifs_file_list_lock);
>>
>> + if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) && last_open_file)
>> + invalidate_remote_inode(inode);
>> +
>
> Now that I think about it...this looks racy. Suppose someone races in
> after you set last_open_file, opens the file and does a write....
Can you explain what bad happens in this case?
>
> I think you'd be better served by setting the invalid_mapping flag on
> the cifs_i instead and letting the normal revalidation codepath handle
> this. The cache will then be invalidated the next time
> cifs_revalidate_file/dentry is run.
>
>> if (!tcon->need_reconnect && !cifs_file->invalidHandle) {
>> int xid, rc;
>>
>
--
Best regards,
Pavel Shilovsky.
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