Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

fs/logfs/dev_mtd.c

@@ -60,7 +60,7 @@ static int mtd_write(struct super_block *sb, loff_t ofs, size_t len, void *buf)
  * asynchronous properties.  So just to prevent the first implementor of such
  * a thing from breaking logfs in 2350, we do the usual pointless dance to
  * declare a completion variable and wait for completion before returning
- * from mtd_erase().  What an excercise in futility!
+ * from mtd_erase().  What an exercise in futility!
  */
 static void logfs_erase_callback(struct erase_info *ei)
 {

fs/logfs/dir.c

@@ -92,7 +92,7 @@ static int beyond_eof(struct inode *inode, loff_t bix)
  * so short names (len <= 9) don't even occupy the complete 32bit name
  * space.  A prime >256 ensures short names quickly spread the 32bit
  * name space.  Add about 26 for the estimated amount of information
- * of each character and pick a prime nearby, preferrably a bit-sparse
+ * of each character and pick a prime nearby, preferably a bit-sparse
  * one.
  */
 static u32 hash_32(const char *s, int len, u32 seed)

fs/logfs/readwrite.c

@@ -1616,7 +1616,7 @@ int logfs_rewrite_block(struct inode *inode, u64 bix, u64 ofs,
 		err = logfs_write_buf(inode, page, flags);
 		if (!err && shrink_level(gc_level) == 0) {
 			/* Rewrite cannot mark the inode dirty but has to
-			 * write it immediatly.
+			 * write it immediately.
 			 * Q: Can't we just create an alias for the inode
 			 * instead?  And if not, why not?
 			 */