ср, 13 июн. 2018 г. в 13:50, Ronnie Sahlberg <lsahlber@xxxxxxxxxx>:
>
> Use a read lease for the cached root fid so that we can detect
> when the content of the directory changes (via a break) at which time
> we close the handle. On next access to the root the handle will be reopened
> and cached again.
>
> Signed-off-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
> ---
> fs/cifs/cifsglob.h | 12 +++++++++---
> fs/cifs/cifsproto.h | 1 +
> fs/cifs/cifssmb.c | 8 ++++----
> fs/cifs/misc.c | 7 ++++---
> fs/cifs/smb2misc.c | 16 +++++++++++++++-
> fs/cifs/smb2ops.c | 34 +++++++++++++++++++++++++---------
> 6 files changed, 58 insertions(+), 20 deletions(-)
>
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index 1efa2e65bc1a..ff71fbd619bf 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -883,6 +883,14 @@ cap_unix(struct cifs_ses *ses)
> return ses->server->vals->cap_unix & ses->capabilities;
> }
>
> +struct cached_fid {
> + bool is_valid:1; /* Do we have a useable root fid */
> + struct cifs_fid *fid;
> + struct mutex fid_mutex;
> + struct cifs_tcon *tcon;
> + struct work_struct lease_break;
> +};
> +
> /*
> * there is one of these for each connection to a resource on a particular
> * session
> @@ -987,9 +995,7 @@ struct cifs_tcon {
> struct fscache_cookie *fscache; /* cookie for share */
> #endif
> struct list_head pending_opens; /* list of incomplete opens */
> - bool valid_root_fid:1; /* Do we have a useable root fid */
> - struct mutex prfid_mutex; /* prevents reopen race after dead ses*/
> - struct cifs_fid *prfid; /* handle to the directory at top of share */
> + struct cached_fid crfid; /* Cached root fid */
> /* BB add field for back pointer to sb struct(s)? */
> };
>
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index e19c27196182..03018be17283 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -548,6 +548,7 @@ enum securityEnum cifs_select_sectype(struct TCP_Server_Info *,
> struct cifs_aio_ctx *cifs_aio_ctx_alloc(void);
> void cifs_aio_ctx_release(struct kref *refcount);
> int setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw);
> +void smb2_cached_lease_break(struct work_struct *work);
>
> int cifs_alloc_hash(const char *name, struct crypto_shash **shash,
> struct sdesc **sdesc);
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index 5aca336642c0..c23cd2c9cc25 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -107,10 +107,10 @@ cifs_mark_open_files_invalid(struct cifs_tcon *tcon)
> }
> spin_unlock(&tcon->open_file_lock);
>
> - mutex_lock(&tcon->prfid_mutex);
> - tcon->valid_root_fid = false;
> - memset(tcon->prfid, 0, sizeof(struct cifs_fid));
> - mutex_unlock(&tcon->prfid_mutex);
> + mutex_lock(&tcon->crfid.fid_mutex);
> + tcon->crfid.is_valid = false;
> + memset(tcon->crfid.fid, 0, sizeof(struct cifs_fid));
> + mutex_unlock(&tcon->crfid.fid_mutex);
>
> /*
> * BB Add call to invalidate_inodes(sb) for all superblocks mounted
> diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
> index f90d4ad6624c..0da609cfac95 100644
> --- a/fs/cifs/misc.c
> +++ b/fs/cifs/misc.c
> @@ -117,8 +117,9 @@ tconInfoAlloc(void)
> INIT_LIST_HEAD(&ret_buf->openFileList);
> INIT_LIST_HEAD(&ret_buf->tcon_list);
> spin_lock_init(&ret_buf->open_file_lock);
> - mutex_init(&ret_buf->prfid_mutex);
> - ret_buf->prfid = kzalloc(sizeof(struct cifs_fid), GFP_KERNEL);
> + mutex_init(&ret_buf->crfid.fid_mutex);
> + ret_buf->crfid.fid = kzalloc(sizeof(struct cifs_fid),
> + GFP_KERNEL);
> #ifdef CONFIG_CIFS_STATS
> spin_lock_init(&ret_buf->stat_lock);
> #endif
> @@ -136,7 +137,7 @@ tconInfoFree(struct cifs_tcon *buf_to_free)
> atomic_dec(&tconInfoAllocCount);
> kfree(buf_to_free->nativeFileSystem);
> kzfree(buf_to_free->password);
> - kfree(buf_to_free->prfid);
> + kfree(buf_to_free->crfid.fid);
> kfree(buf_to_free);
> }
>
> diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
> index e2bec47c6845..0de87ca33e2e 100644
> --- a/fs/cifs/smb2misc.c
> +++ b/fs/cifs/smb2misc.c
> @@ -492,10 +492,11 @@ cifs_ses_oplock_break(struct work_struct *work)
> {
> struct smb2_lease_break_work *lw = container_of(work,
> struct smb2_lease_break_work, lease_break);
> - int rc;
> + int rc = 0;
>
> rc = SMB2_lease_break(0, tlink_tcon(lw->tlink), lw->lease_key,
> lw->lease_state);
> +
> cifs_dbg(FYI, "Lease release rc %d\n", rc);
> cifs_put_tlink(lw->tlink);
> kfree(lw);
> @@ -561,6 +562,7 @@ smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
>
> open->oplock = lease_state;
> }
> +
> return found;
> }
>
> @@ -603,6 +605,18 @@ smb2_is_valid_lease_break(char *buffer)
> return true;
> }
> spin_unlock(&tcon->open_file_lock);
> +
> + if (tcon->crfid.is_valid &&
> + !memcmp(rsp->LeaseKey,
> + tcon->crfid.fid->lease_key,
> + SMB2_LEASE_KEY_SIZE)) {
> + INIT_WORK(&tcon->crfid.lease_break,
> + smb2_cached_lease_break);
> + queue_work(cifsiod_wq,
> + &tcon->crfid.lease_break);
> + spin_unlock(&cifs_tcp_ses_lock);
> + return true;
> + }
> }
> }
> }
> diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
> index d1648a9753d0..9153407f97e8 100644
> --- a/fs/cifs/smb2ops.c
> +++ b/fs/cifs/smb2ops.c
> @@ -323,6 +323,21 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
> }
> #endif /* STATS2 */
>
> +void
> +smb2_cached_lease_break(struct work_struct *work)
> +{
> + struct cached_fid *cfid = container_of(work,
> + struct cached_fid, lease_break);
> + mutex_lock(&cfid->fid_mutex);
> + if (cfid->is_valid) {
> + cifs_dbg(FYI, "clear cached root file handle\n");
> + SMB2_close(0, cfid->tcon, cfid->fid->persistent_fid,
> + cfid->fid->volatile_fid);
> + cfid->is_valid = false;
> + }
> + mutex_unlock(&cfid->fid_mutex);
> +}
> +
Let's consider the following scenario:
1) thread1 obtained FID in open_shroot()
2) lease break is received
3) thread2: smb2_cached_lease_break() closes the cached root file handle
4) thread1 uses the old closed root file handle.
In the step #4, nothing will let thread1 know that the FID is stale
and it needs to refresh it. Can we use existing cifsFileInfo structure
with a ref counter for a root file handle too? This should help
resolving the issue described above.
--
Best regards,
Pavel Shilovsky
--
To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
