Set actual compressed page size also on read code path to buffer pool so

that we can later use it to avoid unnecessary trim operations. 

storage/innobase/buf/buf0rea.cc

@@ -185,7 +185,7 @@ buf_read_page_low(
 		*err = fil_io(OS_FILE_READ | wake_later
 			      | ignore_nonexistent_pages,
 			      sync, space, zip_size, offset, 0, zip_size,
-			      bpage->zip.data, bpage, 0);
+			      bpage->zip.data, bpage, &bpage->write_size);
 	} else {
 		ut_a(buf_page_get_state(bpage) == BUF_BLOCK_FILE_PAGE);
 

storage/innobase/fil/fil0pagecompress.cc

@@ -226,7 +226,9 @@ fil_decompress_page(
 	byte*           page_buf,      /*!< in: preallocated buffer or NULL */
 	byte*           buf,           /*!< out: buffer from which to read; in aio
 				       this must be appropriately aligned */
-        ulint           len)           /*!< in: length of output buffer.*/
+        ulint           len,           /*!< in: length of output buffer.*/
+	ulint*		write_size)    /*!< in/out: Actual payload size of
+				       the compressed data. */
 {
         int err = 0;
         ulint actual_size = 0;
@@ -277,6 +279,12 @@ fil_decompress_page(
 		ut_error;
 	}
 
+	/* Store actual payload size of the compressed data. This pointer
+	points to buffer pool. */
+	if (write_size) {
+		*write_size = actual_size;
+	}
+
 	if (compression_alg == FIL_PAGE_COMPRESSION_ZLIB) {
 
 #ifdef UNIV_DEBUG

storage/innobase/include/fil0pagecompress.h

@@ -97,7 +97,9 @@ fil_decompress_page(
 	byte*           page_buf,      /*!< in: preallocated buffer or NULL */
 	byte*           buf,           /*!< out: buffer from which to read; in aio
 				       this must be appropriately aligned */
-        ulint           len);          /*!< in: length of output buffer.*/
+        ulint           len,           /*!< in: length of output buffer.*/
+	ulint*		write_size);   /*!< in/out: Actual payload size of
+				       the compressed data. */
 
 /****************************************************************//**
 Get space id from fil node

storage/innobase/os/os0file.cc

@@ -2821,7 +2821,7 @@ try_again:
 
 	if (ret && len == n) {
 		if (fil_page_is_compressed((byte *)buf)) {
-		        fil_decompress_page(NULL, (byte *)buf, len);
+		        fil_decompress_page(NULL, (byte *)buf, len, NULL);
 		}
 		return(TRUE);
 	}
@@ -2836,7 +2836,7 @@ try_again:
 
 	if ((ulint) ret == n) {
 		if (fil_page_is_compressed((byte *)buf)) {
-		        fil_decompress_page(NULL, (byte *)buf, n);
+		        fil_decompress_page(NULL, (byte *)buf, n, NULL);
 		}
 
 		return(TRUE);
@@ -5164,7 +5164,7 @@ os_aio_windows_handle(
 
 	        if (slot->type == OS_FILE_READ) {
 			if (fil_page_is_compressed(slot->buf)) {
-				fil_decompress_page(slot->page_buf, slot->buf, slot->len);
+				fil_decompress_page(slot->page_buf, slot->buf, slot->len, slot->write_size);
 			}
 		} else {
 			if (slot->page_compress_success && fil_page_is_compressed(slot->page_buf)) {
@@ -5278,7 +5278,7 @@ retry:
 
 				if (slot->type == OS_FILE_READ) {
 					if (fil_page_is_compressed(slot->buf)) {
-						fil_decompress_page(slot->page_buf, slot->buf, slot->len);
+						fil_decompress_page(slot->page_buf, slot->buf, slot->len, slot->write_size);
 					}
 				} else {
 					if (slot->page_compress_success &&
@@ -6219,7 +6219,9 @@ os_file_trim(
 		"  InnoDB: [Warning] fallocate not supported on this installation."
 		"  InnoDB: Disabling fallocate for now.");
 	os_fallocate_failed = TRUE;
-	slot->write_size = NULL;
+	if (slot->write_size) {
+		*slot->write_size = 0;
+	}
 
 #endif /* HAVE_FALLOCATE ... */
 

storage/xtradb/buf/buf0rea.cc

@@ -237,7 +237,7 @@ not_to_recover:
 		*err = _fil_io(OS_FILE_READ | wake_later
 			      | ignore_nonexistent_pages,
 			      sync, space, 0, offset, 0, UNIV_PAGE_SIZE,
-			      ((buf_block_t*) bpage)->frame, bpage, 0, trx);
+			      ((buf_block_t*) bpage)->frame, bpage, &bpage->write_size, trx);
 	}
 
 	if (sync) {

storage/xtradb/fil/fil0pagecompress.cc

@@ -222,7 +222,9 @@ fil_decompress_page(
 	byte*           page_buf,      /*!< in: preallocated buffer or NULL */
 	byte*           buf,           /*!< out: buffer from which to read; in aio
 				       this must be appropriately aligned */
-        ulint           len)           /*!< in: length of output buffer.*/
+        ulint           len,           /*!< in: length of output buffer.*/
+	ulint*		write_size)    /*!< in/out: Actual payload size of
+				       the compressed data. */
 {
         int err = 0;
         ulint actual_size = 0;
@@ -273,6 +275,12 @@ fil_decompress_page(
 		ut_error;
 	}
 
+	/* Store actual payload size of the compressed data. This pointer
+	points to buffer pool. */
+	if (write_size) {
+		*write_size = actual_size;
+	}
+
 	if (compression_alg == FIL_PAGE_COMPRESSION_ZLIB) {
 
 #ifdef UNIV_DEBUG

storage/xtradb/include/fil0pagecompress.h

@@ -97,7 +97,9 @@ fil_decompress_page(
 	byte*           page_buf,      /*!< in: preallocated buffer or NULL */
 	byte*           buf,           /*!< out: buffer from which to read; in aio
 				       this must be appropriately aligned */
-        ulint           len);          /*!< in: length of output buffer.*/
+        ulint           len,           /*!< in: length of output buffer.*/
+	ulint*		write_size);   /*!< in/out: Actual payload size of
+				       the compressed data. */
 
 /****************************************************************//**
 Get space id from fil node

storage/xtradb/os/os0file.cc

@@ -3009,7 +3009,7 @@ try_again:
 
 	if (ret && len == n) {
 		if (fil_page_is_compressed((byte *)buf)) {
-		        fil_decompress_page(NULL, (byte *)buf, len);
+		        fil_decompress_page(NULL, (byte *)buf, len, NULL);
 		}
 		return(TRUE);
 	}
@@ -3025,7 +3025,7 @@ try_again:
 	if ((ulint) ret == n) {
 
 		if (fil_page_is_compressed((byte *)buf)) {
-		        fil_decompress_page(NULL, (byte *)buf, n);
+		        fil_decompress_page(NULL, (byte *)buf, n, NULL);
 		}
 
 		return(TRUE);
@@ -3129,7 +3129,7 @@ try_again:
 	if ((ulint) ret == n) {
 
 		if (fil_page_is_compressed((byte *)buf)) {
-		        fil_decompress_page(NULL, (byte *)buf, n);
+		        fil_decompress_page(NULL, (byte *)buf, n, NULL);
 		}
 
 		return(TRUE);
@@ -5223,7 +5223,7 @@ os_aio_windows_handle(
 
 	        if (slot->type == OS_FILE_READ) {
 			if (fil_page_is_compressed(slot->buf)) {
-				fil_decompress_page(slot->page_buf, slot->buf, slot->len);
+				fil_decompress_page(slot->page_buf, slot->buf, slot->len, slot->write_size);
 			}
 		} else {
 			if (slot->page_compress_success && fil_page_is_compressed(slot->page_buf)) {
@@ -5337,7 +5337,7 @@ retry:
 
 				if (slot->type == OS_FILE_READ) {
 					if (fil_page_is_compressed(slot->buf)) {
-						fil_decompress_page(slot->page_buf, slot->buf, slot->len);
+						fil_decompress_page(slot->page_buf, slot->buf, slot->len, slot->write_size);
 					}
 				} else {
 					if (slot->page_compress_success &&
@@ -6284,7 +6284,9 @@ os_file_trim(
 		"  InnoDB: [Warning] fallocate not supported on this installation."
 		"  InnoDB: Disabling fallocate for now.");
 	os_fallocate_failed = TRUE;
-	slot->write_size = NULL;
+	if (slot->write_size) {
+		*slot->write_size = 0;
+	}
 
 #endif /* HAVE_FALLOCATE ... */