[PATCH 4/4 V2] kvm tools: Complete missing segments in a iov op using regular op

[Sasha Levin <levinsasha928@xxxxxxxxx>]

If any of the iov operations return mid-block, use regular ops to complete the current block and continue using iov ops.

Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
---
 tools/kvm/read-write.c |   58 ++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/tools/kvm/read-write.c b/tools/kvm/read-write.c
index 0c995c8..bf2e4a0 100644
--- a/tools/kvm/read-write.c
+++ b/tools/kvm/read-write.c
@@ -189,10 +189,10 @@ static inline ssize_t get_iov_size(const struct iovec *iov, int iovcnt)
 }
 
 static inline void shift_iovec(const struct iovec **iov, int *iovcnt,
-				size_t nr, ssize_t *total, size_t *count, off_t *offset)
+				ssize_t *nr, ssize_t *total, size_t *count, off_t *offset)
 {
-	while (nr >= (*iov)->iov_len) {
-		nr -= (*iov)->iov_len;
+	while ((size_t)*nr >= (*iov)->iov_len) {
+		*nr -= (*iov)->iov_len;
 		*total += (*iov)->iov_len;
 		*count -= (*iov)->iov_len;
 		if (offset)
@@ -218,7 +218,18 @@ ssize_t readv_in_full(int fd, const struct iovec *iov, int iovcnt)
 			return -1;
 		}
 
-		shift_iovec(&iov, &iovcnt, nr, &total, &count, NULL);
+		shift_iovec(&iov, &iovcnt, &nr, &total, &count, NULL);
+
+		while (nr > 0) {
+			ssize_t nr_readagain;
+			nr_readagain = xread(fd, iov->iov_base + nr,
+									iov->iov_len - nr);
+			if (nr_readagain <= 0)
+				return total;
+
+			nr += nr_readagain;
+			shift_iovec(&iov, &iovcnt, &nr, &total, &count, NULL);
+		}
 	}
 
 	return total;
@@ -240,7 +251,18 @@ ssize_t writev_in_full(int fd, const struct iovec *iov, int iovcnt)
 			return -1;
 		}
 
-		shift_iovec(&iov, &iovcnt, nr, &total, &count, NULL);
+		shift_iovec(&iov, &iovcnt, &nr, &total, &count, NULL);
+
+		while (nr > 0) {
+			ssize_t nr_writeagain;
+			nr_writeagain = xwrite(fd, iov->iov_base + nr,
+									iov->iov_len - nr);
+			if (nr_writeagain <= 0)
+				return total;
+
+			nr += nr_writeagain;
+			shift_iovec(&iov, &iovcnt, &nr, &total, &count, NULL);
+		}
 	}
 
 	return total;
@@ -288,7 +310,18 @@ ssize_t preadv_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset
 			return -1;
 		}
 
-		shift_iovec(&iov, &iovcnt, nr, &total, &count, &offset);
+		shift_iovec(&iov, &iovcnt, &nr, &total, &count, &offset);
+
+		while (nr > 0) {
+			ssize_t nr_readagain;
+			nr_readagain = xpread(fd, iov->iov_base + nr,
+									iov->iov_len - nr, offset + nr);
+			if (nr_readagain <= 0)
+				return total;
+
+			nr += nr_readagain;
+			shift_iovec(&iov, &iovcnt, &nr, &total, &count, &offset);
+		}
 	}
 
 	return total;
@@ -310,7 +343,18 @@ ssize_t pwritev_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offse
 			return -1;
 		}
 
-		shift_iovec(&iov, &iovcnt, nr, &total, &count, &offset);
+		shift_iovec(&iov, &iovcnt, &nr, &total, &count, &offset);
+
+		while (nr > 0) {
+			ssize_t nr_writeagain;
+			nr_writeagain = xpwrite(fd, iov->iov_base + nr,
+									iov->iov_len - nr, offset + nr);
+			if (nr_writeagain <= 0)
+				return total;
+
+			nr += nr_writeagain;
+			shift_iovec(&iov, &iovcnt, &nr, &total, &count, &offset);
+		}
 	}
 
 	return total;
-- 
1.7.5.rc1

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