libglusterfs: cleanup iovec functions

This patch cleans some iovec code and creates two additional helper
functions to simplify management of iovec structures.

  iov_range_copy(struct iovec *dst, uint32_t dst_count, uint32_t dst_offset,
                 struct iovec *src, uint32_t src_count, uint32_t src_offset,
                 uint32_t size);

    This function copies up to 'size' bytes from 'src' at offset
    'src_offset' to 'dst' at 'dst_offset'. It returns the number of
    bytes copied.

  iov_skip(struct iovec *iovec, uint32_t count, uint32_t size);

    This function removes the initial 'size' bytes from 'iovec' and
    returns the updated number of iovec vectors remaining.

The signature of iov_subset() has also been modified to make it safer
and easier to use. The new signature is:

  iov_subset(struct iovec *src, int src_count, uint32_t start, uint32_t size,
             struct iovec **dst, int32_t dst_count);

    This function creates a new iovec array containing the subset of the
    'src' vector starting at 'start' with size 'size'. The resulting
    array is allocated if '*dst' is NULL, or copied to '*dst' if it fits
    (based on 'dst_count'). It returns the number of iovec vectors used.

A new set of functions to iterate through an iovec array have been
created. They can be used to simplify the implementation of other
iovec-based helper functions.

Change-Id: Ia5fe57e388e23392a8d6cdab17670e337cadd587
Updates: bz#1193929
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

1 files changed, 2 insertions, 8 deletions

diff --git a/xlators/features/quota/src/quota.c b/xlators/features/quota/src/quota.c
index 1335386a197..c787028e7b3 100644
--- a/xlators/features/quota/src/quota.c
+++ b/xlators/features/quota/src/quota.c
@@ -1769,19 +1769,13 @@ quota_writev_helper(call_frame_t *frame, xlator_t *this, fd_t *fd,
 
         if ((op_errno == EDQUOT) && (local->space_available > 0)) {
             new_count = iov_subset(vector, count, 0, local->space_available,
-                                   NULL);
-
-            new_vector = GF_CALLOC(new_count, sizeof(struct iovec),
-                                   gf_common_mt_iovec);
-            if (new_vector == NULL) {
+                                   &new_vector, 0);
+            if (new_count < 0) {
                 local->op_ret = -1;
                 local->op_errno = ENOMEM;
                 goto unwind;
             }
 
-            new_count = iov_subset(vector, count, 0, local->space_available,
-                                   new_vector);
-
             vector = new_vector;
             count = new_count;
         } else if (op_errno == ENOENT || op_errno == ESTALE) {