[PATCH v3 1/3] file-posix:add the tracking of the zones write pointers

[Sam Li]

Since Linux doesn't have a user API to issue zone append operations to
zoned devices from user space, the file-posix driver is modified to add
zone append emulation using regular writes. To do this, the file-posix
driver tracks the wp location of all zones of the device. It uses an
array of uint64_t. The most significant bit of each wp location indicates
if the zone type is conventional zones.

The zones wp can be changed due to the following operations issued:
- zone reset: change the wp to the start offset of that zone
- zone finish: change to the end location of that zone
- write to a zone
- zone append

Signed-off-by: Sam Li <faithilikerun@gmail.com>
---
 block/file-posix.c               | 158 +++++++++++++++++++++++++++++++
 include/block/block-common.h     |  14 +++
 include/block/block_int-common.h |   5 +
 3 files changed, 177 insertions(+)

diff --git a/block/file-posix.c b/block/file-posix.c
index a9d347292e..17c0b58158 100755
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -206,6 +206,7 @@ typedef struct RawPosixAIOData {
         struct {
             struct iovec *iov;
             int niov;
+            int64_t *append_sector;
         } io;
         struct {
             uint64_t cmd;
@@ -226,6 +227,7 @@ typedef struct RawPosixAIOData {
         struct {
             unsigned long zone_op;
             const char *zone_op_name;
+            bool all;
         } zone_mgmt;
     };
 } RawPosixAIOData;
@@ -1331,6 +1333,67 @@ static int hdev_get_max_segments(int fd, struct stat 
*st) {
 #endif
 }
 
+#if defined(CONFIG_BLKZONED)
+static int get_zones_wp(int64_t offset, int fd, BlockZoneWps *wps,
+                        unsigned int nrz) {
+    struct blk_zone *blkz;
+    int64_t rep_size;
+    int64_t sector = offset >> BDRV_SECTOR_BITS;
+    int ret, n = 0, i = 0;
+    rep_size = sizeof(struct blk_zone_report) + nrz * sizeof(struct blk_zone);
+    g_autofree struct blk_zone_report *rep = NULL;
+
+    rep = g_malloc(rep_size);
+    blkz = (struct blk_zone *)(rep + 1);
+    while (n < nrz) {
+        memset(rep, 0, rep_size);
+        rep->sector = sector;
+        rep->nr_zones = nrz - n;
+
+        do {
+            ret = ioctl(fd, BLKREPORTZONE, rep);
+        } while (ret != 0 && errno == EINTR);
+        if (ret != 0) {
+            error_report("%d: ioctl BLKREPORTZONE at %" PRId64 " failed %d",
+                    fd, offset, errno);
+            return -errno;
+        }
+
+        if (!rep->nr_zones) {
+            break;
+        }
+
+        for (i = 0; i < rep->nr_zones; i++, n++) {
+            /*
+             * The wp tracking cares only about sequential writes required and
+             * sequential write preferred zones so that the wp can advance to
+             * the right location.
+             * Use the most significant bit of the wp location to indicate the
+             * zone type: 0 for SWR/SWP zones and 1 for conventional zones.
+             */
+            if (!(blkz[i].type != BLK_ZONE_TYPE_CONVENTIONAL)) {
+                wps->wp[i] += 1ULL << 63;
+            } else {
+                wps->wp[i] = blkz[i].wp << BDRV_SECTOR_BITS;
+            }
+        }
+        sector = blkz[i-1].start + blkz[i-1].len;
+    }
+
+    return 0;
+}
+
+static void update_zones_wp(int64_t offset, int fd, BlockZoneWps *wps,
+                            unsigned int nrz) {
+    qemu_mutex_lock(&wps->lock);
+    if (get_zones_wp(offset, fd, wps, nrz) < 0) {
+        error_report("report zone wp failed");
+        return;
+    }
+    qemu_mutex_unlock(&wps->lock);
+}
+#endif
+
 static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     BDRVRawState *s = bs->opaque;
@@ -1414,6 +1477,19 @@ static void raw_refresh_limits(BlockDriverState *bs, 
Error **errp)
             error_report("Invalid device capacity %" PRId64 " bytes ", 
bs->bl.capacity);
             return;
         }
+
+        ret = get_sysfs_long_val(&st, "physical_block_size");
+        if (ret >= 0) {
+            bs->bl.write_granularity = ret;
+        }
+
+        bs->bl.wps = g_malloc(sizeof(BlockZoneWps) + sizeof(int64_t) * ret);
+        if (get_zones_wp(0, s->fd, bs->bl.wps, ret) < 0){
+            error_report("report wps failed");
+            g_free(bs->bl.wps);
+            return;
+        }
+        qemu_mutex_init(&bs->bl.wps->lock);
     }
 }
 
@@ -1651,6 +1727,20 @@ static int handle_aiocb_rw(void *opaque)
     ssize_t nbytes;
     char *buf;
 
+    /*
+     * The offset of regular writes, append writes is the wp location
+     * of that zone.
+     */
+    if (aiocb->aio_type & QEMU_AIO_WRITE) {
+        if (aiocb->bs->bl.zone_size > 0) {
+            BlockZoneWps *wps = aiocb->bs->bl.wps;
+            qemu_mutex_lock(&wps->lock);
+            aiocb->aio_offset = wps->wp[aiocb->aio_offset /
+                                        aiocb->bs->bl.zone_size];
+            qemu_mutex_unlock(&wps->lock);
+        }
+    }
+
     if (!(aiocb->aio_type & QEMU_AIO_MISALIGNED)) {
         /*
          * If there is just a single buffer, and it is properly aligned
@@ -1725,6 +1815,24 @@ static int handle_aiocb_rw(void *opaque)
 
 out:
     if (nbytes == aiocb->aio_nbytes) {
+#if defined(CONFIG_BLKZONED)
+        if (aiocb->aio_type & QEMU_AIO_WRITE) {
+            BlockZoneWps *wps = aiocb->bs->bl.wps;
+            int index = aiocb->aio_offset / aiocb->bs->bl.zone_size;
+            if (wps) {
+                qemu_mutex_lock(&wps->lock);
+                if (!BDRV_ZT_IS_CONV(wps->wp[index])) {
+                    uint64_t wend_offset =
+                            aiocb->aio_offset + aiocb->aio_nbytes;
+                    /* Advance the wp if needed */
+                    if (wend_offset > wps->wp[index]){
+                        wps->wp[index] = wend_offset;
+                    }
+                }
+                qemu_mutex_unlock(&wps->lock);
+            }
+        }
+#endif
         return 0;
     } else if (nbytes >= 0 && nbytes < aiocb->aio_nbytes) {
         if (aiocb->aio_type & QEMU_AIO_WRITE) {
@@ -1736,6 +1844,12 @@ out:
         }
     } else {
         assert(nbytes < 0);
+#if defined(CONFIG_BLKZONED)
+        if (aiocb->aio_type & QEMU_AIO_WRITE) {
+            update_zones_wp(0, aiocb->aio_fildes, aiocb->bs->bl.wps,
+                            aiocb->bs->bl.nr_zones);
+        }
+#endif
         return nbytes;
     }
 }
@@ -2022,12 +2136,17 @@ static int handle_aiocb_zone_report(void *opaque) {
 #if defined(CONFIG_BLKZONED)
 static int handle_aiocb_zone_mgmt(void *opaque) {
     RawPosixAIOData *aiocb = opaque;
+    BlockDriverState *bs = aiocb->bs;
     int fd = aiocb->aio_fildes;
     int64_t sector = aiocb->aio_offset / 512;
     int64_t nr_sectors = aiocb->aio_nbytes / 512;
+    uint64_t wend_offset;
     struct blk_zone_range range;
     int ret;
 
+    BlockZoneWps *wps = bs->bl.wps;
+    int index = aiocb->aio_offset / bs->bl.zone_size;
+
     /* Execute the operation */
     range.sector = sector;
     range.nr_sectors = nr_sectors;
@@ -2035,11 +2154,41 @@ static int handle_aiocb_zone_mgmt(void *opaque) {
         ret = ioctl(fd, aiocb->zone_mgmt.zone_op, &range);
     } while (ret != 0 && errno == EINTR);
     if (ret != 0) {
+        update_zones_wp(0, aiocb->aio_fildes, aiocb->bs->bl.wps,
+                        aiocb->bs->bl.nr_zones);
         ret = -errno;
         error_report("ioctl %s failed %d", aiocb->zone_mgmt.zone_op_name,
                      ret);
         return ret;
     }
+
+    qemu_mutex_lock(&wps->lock);
+    if (!BDRV_ZT_IS_CONV(wps->wp[index])) {
+         /*
+         * The zoned device allows the last zone smaller that the zone size.
+         */
+        if (aiocb->aio_nbytes < bs->bl.zone_size) {
+            wend_offset = aiocb->aio_offset + aiocb->aio_nbytes;
+        } else {
+            wend_offset = aiocb->aio_offset + bs->bl.zone_size;
+        }
+
+        if (aiocb->aio_offset != wps->wp[index] &&
+            aiocb->zone_mgmt.zone_op == BLKRESETZONE) {
+            if (aiocb->zone_mgmt.all) {
+                for (int i = 0; i < bs->bl.nr_zones; ++i) {
+                    wps->wp[i] = i * bs->bl.zone_size;
+                }
+            } else {
+                wps->wp[index] = aiocb->aio_offset;
+            }
+        } else if (aiocb->aio_offset != wps->wp[index] &&
+            aiocb->zone_mgmt.zone_op == BLKFINISHZONE) {
+            wps->wp[index] = wend_offset;
+        }
+    }
+    qemu_mutex_unlock(&wps->lock);
+
     return ret;
 }
 #endif
@@ -2480,6 +2629,12 @@ static void raw_close(BlockDriverState *bs)
     BDRVRawState *s = bs->opaque;
 
     if (s->fd >= 0) {
+#if defined(CONFIG_BLKZONED)
+        if (bs->bl.wps) {
+            qemu_mutex_destroy(&bs->bl.wps->lock);
+            g_free(bs->bl.wps);
+        }
+#endif
         qemu_close(s->fd);
         s->fd = -1;
     }
@@ -3278,6 +3433,7 @@ static int coroutine_fn raw_co_zone_mgmt(BlockDriverState 
*bs, BlockZoneOp op,
     int64_t zone_size, zone_size_mask;
     const char *zone_op_name;
     unsigned long zone_op;
+    bool is_all = false;
 
     zone_size = bs->bl.zone_size;
     zone_size_mask = zone_size - 1;
@@ -3314,6 +3470,7 @@ static int coroutine_fn raw_co_zone_mgmt(BlockDriverState 
*bs, BlockZoneOp op,
     case BLK_ZO_RESET_ALL:
         zone_op_name = "BLKRESETZONE";
         zone_op = BLKRESETZONE;
+        is_all = true;
         break;
     default:
         g_assert_not_reached();
@@ -3328,6 +3485,7 @@ static int coroutine_fn raw_co_zone_mgmt(BlockDriverState 
*bs, BlockZoneOp op,
         .zone_mgmt  = {
             .zone_op = zone_op,
             .zone_op_name = zone_op_name,
+            .all = is_all,
         },
     };
 
diff --git a/include/block/block-common.h b/include/block/block-common.h
index 882de6825e..b8b2dba64a 100644
--- a/include/block/block-common.h
+++ b/include/block/block-common.h
@@ -93,6 +93,14 @@ typedef struct BlockZoneDescriptor {
     BlockZoneCondition cond;
 } BlockZoneDescriptor;
 
+/*
+ * Track write pointers of a zone in bytes.
+ */
+typedef struct BlockZoneWps {
+    QemuMutex lock;
+    uint64_t wp[];
+} BlockZoneWps;
+
 typedef struct BlockDriverInfo {
     /* in bytes, 0 if irrelevant */
     int cluster_size;
@@ -206,6 +214,12 @@ typedef enum {
 #define BDRV_SECTOR_BITS   9
 #define BDRV_SECTOR_SIZE   (1ULL << BDRV_SECTOR_BITS)
 
+/*
+ * Get the first most significant bit of wp. If it is zero, then
+ * the zone type is SWR.
+ */
+#define BDRV_ZT_IS_CONV(wp)    (wp & (1ULL << 63))
+
 #define BDRV_REQUEST_MAX_SECTORS MIN_CONST(SIZE_MAX >> BDRV_SECTOR_BITS, \
                                            INT_MAX >> BDRV_SECTOR_BITS)
 #define BDRV_REQUEST_MAX_BYTES (BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS)
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 37dddc603c..59c2d1316d 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -857,6 +857,11 @@ typedef struct BlockLimits {
 
     /* device capacity expressed in bytes */
     int64_t capacity;
+
+    /* array of write pointers' location of each zone in the zoned device. */
+    BlockZoneWps *wps;
+
+    int64_t write_granularity;
 } BlockLimits;
 
 typedef struct BdrvOpBlocker BdrvOpBlocker;
-- 
2.37.3