On 17.05.2018 13:05, Kirill Tkhai wrote:
Hi, Pasha,

On 17.05.2018 12:40, Pavel Butsykin wrote:
Allow initialization of kdirect only for vstorage/pstorage.

Signed-off-by: Pavel Butsykin <pbutsy...@virtuozzo.com>
---
  drivers/block/ploop/dev.c          |  4 ----
  fs/fuse/kio/pcs/pcs_fuse_kdirect.c | 23 +++++++++++++++++------
  include/linux/fs.h                 |  5 +++++
  3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 0e72656ec8f9..c6094144c7a5 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -3880,10 +3880,6 @@ static int ploop_truncate(struct ploop_device * plo, 
unsigned long arg)
        return err;
  }
-#define IS_PSTORAGE(sb) (sb->s_magic == FUSE_SUPER_MAGIC && \
-                        (!strcmp(sb->s_subtype, "pstorage") || \
-                         !strcmp(sb->s_subtype, "vstorage")))
-
  static int ploop_bd_full(struct backing_dev_info *bdi, long long nr, int root)
  {
        struct ploop_device *plo      = bdi->congested_data;
diff --git a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c 
b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
index b8503d55e246..4b9c4a304571 100644
--- a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
+++ b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
@@ -144,13 +144,24 @@ void kpcs_conn_abort(struct fuse_conn *fc)
  }
static int kpcs_probe(struct fuse_conn *fc, char *name)
-
  {
-       printk("%s TODO IMPLEMENT check fuse_conn args here!\n", __FUNCTION__);
-       if (!strncmp(name, kio_pcs_ops.name, FUSE_KIO_NAME))
-               return 1;
+       if (strncmp(name, kio_pcs_ops.name, FUSE_KIO_NAME)) {
+               printk(KERN_ERR "FUSE: kio_pcs: invalid kio_ops name: %s\n", 
name);

Despite there was printk() without error level modifier (which is not correct),
and printk(KERN_ERR) is better, let's follow the modern Linux kernel style,
which anyway will be requested in case of submitting patches to mainstream.
pr_err() is more likely to use for such the printing (see the rest of pr_* in 
printk.h).


ok, thanks.

+               return 0;
+       }
- return 0;
+       if (!(fc->flags & FUSE_KDIRECT_IO)) {
+               printk(KERN_ERR "FUSE: kio_pcs: kdirect is not enabled\n");
+               return 0;
+       }

I don't think this is needed, since we already check for this bit in 
fuse_fill_super()
before call of fuse_kio_get(). But I'm not insist on this.


And what is the meaning of this check:
"!strncmp(name, kio_pcs_ops.name, FUSE_KIO_NAME)" ?

We also already have this check. I assumed this can protect against
possible mistakes in the future.

+
+       if (!IS_PSTORAGE(fc->sb)) {
+               printk(KERN_ERR "FUSE: kio_pcs: kdirect is only available for"
+                                   "pstorage/vstorage fuse mount\n");
+               return 0;
+       }
+
+       return 1;
  }
@@ -1202,7 +1213,7 @@ err:
  static struct fuse_kio_ops kio_pcs_ops = {
        .name           = "pcs",
        .owner          = THIS_MODULE,
-       .probe          = kpcs_probe, /*TODO: check sb->dev name */
+       .probe          = kpcs_probe,
.conn_init = kpcs_conn_init,
        .conn_fini      = kpcs_conn_fini,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a1dc3521f979..21770550b6c1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1713,6 +1713,11 @@ struct super_block {
        struct list_lru         s_inode_lru ____cacheline_aligned_in_smp;
  };
+#define IS_PSTORAGE(sb) ((sb)->s_magic == FUSE_SUPER_MAGIC && \
+                        (sb)->s_subtype && \
+                        (!strcmp((sb)->s_subtype, "pstorage") || \
+                         !strcmp((sb)->s_subtype, "vstorage")))
+
  extern const unsigned super_block_wrapper_version;
  struct super_block_wrapper {
        struct super_block sb;


Thanks,
Kirill

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