exofs: Write sbi->s_nextid as part of the Create command

Before when creating a new inode, we'd set the sb->s_dirt flag,
and sometime later the system would write out s_nextid as part
of the sb_info. Also on inode sync we would force the sb sync
as well.

Define the s_nextid as a new partition attribute and set it
every time we create a new object.
At mount we read it from it's new place.

We now never set sb->s_dirt anywhere in exofs. write_super
is actually never called. The call to exofs_write_super from
exofs_put_super is also removed because the VFS always calls
->sync_fs before calling ->put_super twice.

To stay backward-and-forward compatible we also write the old
s_nextid in the super_block object at unmount, and support zero
length attribute on mount.

This also fixes a BUG where in layouts when group_width was not
a divisor of EXOFS_SUPER_ID (0x10000) the s_nextid was not read
from the device it was written to. Because of the sliding window
layout trick, and because the read was always done from the 0
device but the write was done via the raid engine that might slide
the device view. Now we read and write through the raid engine.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index 681b3cb9b4d..0c713cfbebf 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -1102,6 +1102,7 @@ int __exofs_wait_obj_created(struct exofs_i_info *oi)
         }
         return unlikely(is_bad_inode(&oi->vfs_inode)) ? -EIO : 0;
 }
+
 /*
  * Callback function from exofs_new_inode().  The important thing is that we
  * set the obj_created flag so that other methods know that the object exists on
@@ -1160,7 +1161,6 @@ struct inode *exofs_new_inode(struct inode *dir, int mode)
         sbi = sb->s_fs_info;
 
         inode->i_mapping->backing_dev_info = sb->s_bdi;
-        sb->s_dirt = 1;
         inode_init_owner(inode, dir, mode);
         inode->i_ino = sbi->s_nextid++;
         inode->i_blkbits = EXOFS_BLKSHIFT;
@@ -1171,6 +1171,8 @@ struct inode *exofs_new_inode(struct inode *dir, int mode)
         spin_unlock(&sbi->s_next_gen_lock);
         insert_inode_hash(inode);
 
+        exofs_sbi_write_stats(sbi); /* Make sure new sbi->s_nextid is on disk */
+
         mark_inode_dirty(inode);
 
         ret = exofs_get_io_state(&sbi->layout, &ios);