doc: filesystems : Fix typo in Documentations/filesystems

Correct spelling typo in Documentations/filesystems.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Documentation/filesystems/btrfs.txt

@@ -87,7 +87,7 @@ Unless otherwise specified, all options default to off.
 
   device=<devicepath>
 	Specify a device during mount so that ioctls on the control device
-	can be avoided.  Especialy useful when trying to mount a multi-device
+	can be avoided.  Especially useful when trying to mount a multi-device
 	setup as root.  May be specified multiple times for multiple devices.
 
   discard

Documentation/filesystems/nfs/Exporting

@@ -93,7 +93,7 @@ For a filesystem to be exportable it must:
    2/ make sure that d_splice_alias is used rather than d_add
       when ->lookup finds an inode for a given parent and name.
 
-      If inode is NULL, d_splice_alias(inode, dentry) is eqivalent to
+      If inode is NULL, d_splice_alias(inode, dentry) is equivalent to
 
 		d_add(dentry, inode), NULL
 

Documentation/filesystems/qnx6.txt

@@ -149,7 +149,7 @@ Bitmap system area
 ------------------
 
 The bitmap itself is divided into three parts.
-First the system area, that is split into two halfs.
+First the system area, that is split into two halves.
 Then userspace.
 
 The requirement for a static, fixed preallocated system area comes from how

Documentation/filesystems/xfs.txt

@@ -135,7 +135,7 @@ default behaviour.
 	If the memory cost of 8 log buffers is too high on small
 	systems, then it may be reduced at some cost to performance
 	on metadata intensive workloads. The logbsize option below
-	controls the size of each buffer and so is also relevent to
+	controls the size of each buffer and so is also relevant to
 	this case.
 
   logbsize=value