generic_file_aio_read() cleanups

As akpm points out, there's really no need for generic_file_aio_read to
make a special case of count 0: just loop through nr_segs doing nothing.
And as Harvey Harrison points out, there's no need to reset retval to 0
where it's already 0.

Setting count (or ocount) to 0 before calling generic_segment_checks is
unnecessary too; but reluctantly I'll leave that removal to someone with a
wider range of gcc versions to hand - 4.1.2 and 4.2.1 don't warn about it,
but perhaps others do - I forget which are the warniest versions.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Tested-by: Lawrence Greenfield <leg@google.com>
Cc: Christoph Rohland <hans-christoph.rohland@sap.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 23 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 6343f3c841b7..7675b91f4f63 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1197,7 +1197,6 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 
                 mapping = filp->f_mapping;
                 inode = mapping->host;
-                retval = 0;
                 if (!count)
                         goto out; /* skip atime */
                 size = i_size_read(inode);
@@ -1209,33 +1208,30 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
                         }
                         if (retval > 0)
                                 *ppos = pos + retval;
-                }
-                if (likely(retval != 0)) {
-                        file_accessed(filp);
-                        goto out;
+                        if (retval) {
+                                file_accessed(filp);
+                                goto out;
+                        }
                 }
         }
 
-        retval = 0;
-        if (count) {
-                for (seg = 0; seg < nr_segs; seg++) {
-                        read_descriptor_t desc;
+        for (seg = 0; seg < nr_segs; seg++) {
+                read_descriptor_t desc;
 
-                        desc.written = 0;
-                        desc.arg.buf = iov[seg].iov_base;
-                        desc.count = iov[seg].iov_len;
-                        if (desc.count == 0)
-                                continue;
-                        desc.error = 0;
-                        do_generic_file_read(filp,ppos,&desc,file_read_actor);
-                        retval += desc.written;
-                        if (desc.error) {
-                                retval = retval ?: desc.error;
-                                break;
-                        }
-                        if (desc.count > 0)
-                                break;
+                desc.written = 0;
+                desc.arg.buf = iov[seg].iov_base;
+                desc.count = iov[seg].iov_len;
+                if (desc.count == 0)
+                        continue;
+                desc.error = 0;
+                do_generic_file_read(filp, ppos, &desc, file_read_actor);
+                retval += desc.written;
+                if (desc.error) {
+                        retval = retval ?: desc.error;
+                        break;
                 }
+                if (desc.count > 0)
+                        break;
         }
 out:
         return retval;