fuse: add blksize field to fuse_attr

There are cases when the filesystem will be passed the buffer from a single
read or write call, namely:

 1) in 'direct-io' mode (not O_DIRECT), read/write requests don't go
    through the page cache, but go directly to the userspace fs

 2) currently buffered writes are done with single page requests, but
    if Nick's ->perform_write() patch goes it, it will be possible to
    do larger write requests.  But only if the original write() was
    also bigger than a page.

In these cases the filesystem might want to give a hint to the app
about the optimal I/O size.

Allow the userspace filesystem to supply a blksize value to be returned by
stat() and friends.  If the field is zero, it defaults to the old
PAGE_CACHE_SIZE value.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 39 insertions, 5 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 6c83ed052026..3763757f9fe7 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -116,13 +116,19 @@ static void fuse_lookup_init(struct fuse_req *req, struct inode *dir,
                              struct dentry *entry,
                              struct fuse_entry_out *outarg)
 {
+        struct fuse_conn *fc = get_fuse_conn(dir);
+
+        memset(outarg, 0, sizeof(struct fuse_entry_out));
         req->in.h.opcode = FUSE_LOOKUP;
         req->in.h.nodeid = get_node_id(dir);
         req->in.numargs = 1;
         req->in.args[0].size = entry->d_name.len + 1;
         req->in.args[0].value = entry->d_name.name;
         req->out.numargs = 1;
-        req->out.args[0].size = sizeof(struct fuse_entry_out);
+        if (fc->minor < 9)
+                req->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
+        else
+                req->out.args[0].size = sizeof(struct fuse_entry_out);
         req->out.args[0].value = outarg;
 }
 
@@ -356,6 +362,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, int mode,
 
         flags &= ~O_NOCTTY;
         memset(&inarg, 0, sizeof(inarg));
+        memset(&outentry, 0, sizeof(outentry));
         inarg.flags = flags;
         inarg.mode = mode;
         req->in.h.opcode = FUSE_CREATE;
@@ -366,7 +373,10 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, int mode,
         req->in.args[1].size = entry->d_name.len + 1;
         req->in.args[1].value = entry->d_name.name;
         req->out.numargs = 2;
-        req->out.args[0].size = sizeof(outentry);
+        if (fc->minor < 9)
+                req->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
+        else
+                req->out.args[0].size = sizeof(outentry);
         req->out.args[0].value = &outentry;
         req->out.args[1].size = sizeof(outopen);
         req->out.args[1].value = &outopen;
@@ -431,9 +441,13 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_req *req,
                 return PTR_ERR(forget_req);
         }
 
+        memset(&outarg, 0, sizeof(outarg));
         req->in.h.nodeid = get_node_id(dir);
         req->out.numargs = 1;
-        req->out.args[0].size = sizeof(outarg);
+        if (fc->minor < 9)
+                req->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
+        else
+                req->out.args[0].size = sizeof(outarg);
         req->out.args[0].value = &outarg;
         request_send(fc, req);
         err = req->out.h.error;
@@ -724,6 +738,7 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
         spin_unlock(&fc->lock);
 
         memset(&inarg, 0, sizeof(inarg));
+        memset(&outarg, 0, sizeof(outarg));
         /* Directories have separate file-handle space */
         if (file && S_ISREG(inode->i_mode)) {
                 struct fuse_file *ff = file->private_data;
@@ -737,7 +752,10 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
         req->in.args[0].size = sizeof(inarg);
         req->in.args[0].value = &inarg;
         req->out.numargs = 1;
-        req->out.args[0].size = sizeof(outarg);
+        if (fc->minor < 9)
+                req->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
+        else
+                req->out.args[0].size = sizeof(outarg);
         req->out.args[0].value = &outarg;
         request_send(fc, req);
         err = req->out.h.error;
@@ -1102,6 +1120,7 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
                 return PTR_ERR(req);
 
         memset(&inarg, 0, sizeof(inarg));
+        memset(&outarg, 0, sizeof(outarg));
         iattr_to_fattr(attr, &inarg);
         if (file) {
                 struct fuse_file *ff = file->private_data;
@@ -1119,7 +1138,10 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
         req->in.args[0].size = sizeof(inarg);
         req->in.args[0].value = &inarg;
         req->out.numargs = 1;
-        req->out.args[0].size = sizeof(outarg);
+        if (fc->minor < 9)
+                req->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
+        else
+                req->out.args[0].size = sizeof(outarg);
         req->out.args[0].value = &outarg;
         request_send(fc, req);
         err = req->out.h.error;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 49d716036ea7..9a68d6970845 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -148,6 +148,11 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
         inode->i_ctime.tv_sec   = attr->ctime;
         inode->i_ctime.tv_nsec  = attr->ctimensec;
 
+        if (attr->blksize != 0)
+                inode->i_blkbits = ilog2(attr->blksize);
+        else
+                inode->i_blkbits = inode->i_sb->s_blocksize_bits;
+
         /*
          * Don't set the sticky bit in i_mode, unless we want the VFS
          * to check permissions.  This prevents failures due to the
diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index 7d4fa5b25b87..d0c437028c80 100644
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -15,6 +15,7 @@
  *  - new fuse_getattr_in input argument of GETATTR
  *  - add lk_flags in fuse_lk_in
  *  - add lock_owner field to fuse_setattr_in, fuse_read_in and fuse_write_in
+ *  - add blksize field to fuse_attr
  */
 
 #include <asm/types.h>
@@ -53,6 +54,8 @@ struct fuse_attr {
         __u32   uid;
         __u32   gid;
         __u32   rdev;
+        __u32   blksize;
+        __u32   padding;
 };
 
 struct fuse_kstatfs {
@@ -177,6 +180,8 @@ enum fuse_opcode {
 /* The read buffer is required to be at least 8k, but may be much larger */
 #define FUSE_MIN_READ_BUFFER 8192
 
+#define FUSE_COMPAT_ENTRY_OUT_SIZE 120
+
 struct fuse_entry_out {
         __u64   nodeid;         /* Inode ID */
         __u64   generation;     /* Inode generation: nodeid:gen must
@@ -198,6 +203,8 @@ struct fuse_getattr_in {
         __u64   fh;
 };
 
+#define FUSE_COMPAT_ATTR_OUT_SIZE 96
+
 struct fuse_attr_out {
         __u64   attr_valid;     /* Cache timeout for the attributes */
         __u32   attr_valid_nsec;