]> Pileus Git - ~andy/linux/blobdiff - drivers/block/rbd.c
rbd: simplify rbd_dev_v1_probe()
[~andy/linux] / drivers / block / rbd.c
index 0ca959f5c9341cf877720d16080f29d354ab7170..ae223819bbf0e04cffd27b60a8a35abf6d9da2c5 100644 (file)
 #include <linux/ceph/mon_client.h>
 #include <linux/ceph/decode.h>
 #include <linux/parser.h>
+#include <linux/bsearch.h>
 
 #include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/blkdev.h>
+#include <linux/slab.h>
 
 #include "rbd_types.h"
 
  * block device image metadata (in-memory version)
  */
 struct rbd_image_header {
-       /* These four fields never change for a given rbd image */
+       /* These six fields never change for a given rbd image */
        char *object_prefix;
-       u64 features;
        __u8 obj_order;
        __u8 crypt_type;
        __u8 comp_type;
+       u64 stripe_unit;
+       u64 stripe_count;
+       u64 features;           /* Might be changeable someday? */
 
        /* The remaining fields need to be updated occasionally */
        u64 image_size;
        struct ceph_snap_context *snapc;
-       char *snap_names;
-       u64 *snap_sizes;
-
-       u64 stripe_unit;
-       u64 stripe_count;
+       char *snap_names;       /* format 1 only */
+       u64 *snap_sizes;        /* format 1 only */
 };
 
 /*
@@ -343,6 +344,12 @@ static DEFINE_SPINLOCK(rbd_dev_list_lock);
 static LIST_HEAD(rbd_client_list);             /* clients */
 static DEFINE_SPINLOCK(rbd_client_list_lock);
 
+/* Slab caches for frequently-allocated structures */
+
+static struct kmem_cache       *rbd_img_request_cache;
+static struct kmem_cache       *rbd_obj_request_cache;
+static struct kmem_cache       *rbd_segment_name_cache;
+
 static int rbd_img_request_submit(struct rbd_img_request *img_request);
 
 static void rbd_dev_device_release(struct device *dev);
@@ -351,7 +358,7 @@ static ssize_t rbd_add(struct bus_type *bus, const char *buf,
                       size_t count);
 static ssize_t rbd_remove(struct bus_type *bus, const char *buf,
                          size_t count);
-static int rbd_dev_image_probe(struct rbd_device *rbd_dev);
+static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool read_only);
 
 static struct bus_attribute rbd_bus_attrs[] = {
        __ATTR(add, S_IWUSR, NULL, rbd_add),
@@ -720,88 +727,123 @@ static bool rbd_dev_ondisk_valid(struct rbd_image_header_ondisk *ondisk)
 }
 
 /*
- * Create a new header structure, translate header format from the on-disk
- * header.
+ * Fill an rbd image header with information from the given format 1
+ * on-disk header.
  */
-static int rbd_header_from_disk(struct rbd_image_header *header,
+static int rbd_header_from_disk(struct rbd_device *rbd_dev,
                                 struct rbd_image_header_ondisk *ondisk)
 {
+       struct rbd_image_header *header = &rbd_dev->header;
+       bool first_time = header->object_prefix == NULL;
+       struct ceph_snap_context *snapc;
+       char *object_prefix = NULL;
+       char *snap_names = NULL;
+       u64 *snap_sizes = NULL;
        u32 snap_count;
-       size_t len;
        size_t size;
+       int ret = -ENOMEM;
        u32 i;
 
-       memset(header, 0, sizeof (*header));
+       /* Allocate this now to avoid having to handle failure below */
 
-       snap_count = le32_to_cpu(ondisk->snap_count);
+       if (first_time) {
+               size_t len;
 
-       len = strnlen(ondisk->object_prefix, sizeof (ondisk->object_prefix));
-       header->object_prefix = kmalloc(len + 1, GFP_KERNEL);
-       if (!header->object_prefix)
-               return -ENOMEM;
-       memcpy(header->object_prefix, ondisk->object_prefix, len);
-       header->object_prefix[len] = '\0';
+               len = strnlen(ondisk->object_prefix,
+                               sizeof (ondisk->object_prefix));
+               object_prefix = kmalloc(len + 1, GFP_KERNEL);
+               if (!object_prefix)
+                       return -ENOMEM;
+               memcpy(object_prefix, ondisk->object_prefix, len);
+               object_prefix[len] = '\0';
+       }
 
+       /* Allocate the snapshot context and fill it in */
+
+       snap_count = le32_to_cpu(ondisk->snap_count);
+       snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
+       if (!snapc)
+               goto out_err;
+       snapc->seq = le64_to_cpu(ondisk->snap_seq);
        if (snap_count) {
+               struct rbd_image_snap_ondisk *snaps;
                u64 snap_names_len = le64_to_cpu(ondisk->snap_names_len);
 
-               /* Save a copy of the snapshot names */
+               /* We'll keep a copy of the snapshot names... */
 
-               if (snap_names_len > (u64) SIZE_MAX)
-                       return -EIO;
-               header->snap_names = kmalloc(snap_names_len, GFP_KERNEL);
-               if (!header->snap_names)
+               if (snap_names_len > (u64)SIZE_MAX)
+                       goto out_2big;
+               snap_names = kmalloc(snap_names_len, GFP_KERNEL);
+               if (!snap_names)
                        goto out_err;
+
+               /* ...as well as the array of their sizes. */
+
+               size = snap_count * sizeof (*header->snap_sizes);
+               snap_sizes = kmalloc(size, GFP_KERNEL);
+               if (!snap_sizes)
+                       goto out_err;
+
                /*
-                * Note that rbd_dev_v1_header_read() guarantees
-                * the ondisk buffer we're working with has
+                * Copy the names, and fill in each snapshot's id
+                * and size.
+                *
+                * Note that rbd_dev_v1_header_read() guarantees the
+                * ondisk buffer we're working with has
                 * snap_names_len bytes beyond the end of the
                 * snapshot id array, this memcpy() is safe.
                 */
-               memcpy(header->snap_names, &ondisk->snaps[snap_count],
-                       snap_names_len);
+               memcpy(snap_names, &ondisk->snaps[snap_count], snap_names_len);
+               snaps = ondisk->snaps;
+               for (i = 0; i < snap_count; i++) {
+                       snapc->snaps[i] = le64_to_cpu(snaps[i].id);
+                       snap_sizes[i] = le64_to_cpu(snaps[i].image_size);
+               }
+       }
 
-               /* Record each snapshot's size */
+       /* We won't fail any more, fill in the header */
 
-               size = snap_count * sizeof (*header->snap_sizes);
-               header->snap_sizes = kmalloc(size, GFP_KERNEL);
-               if (!header->snap_sizes)
-                       goto out_err;
-               for (i = 0; i < snap_count; i++)
-                       header->snap_sizes[i] =
-                               le64_to_cpu(ondisk->snaps[i].image_size);
+       down_write(&rbd_dev->header_rwsem);
+       if (first_time) {
+               header->object_prefix = object_prefix;
+               header->obj_order = ondisk->options.order;
+               header->crypt_type = ondisk->options.crypt_type;
+               header->comp_type = ondisk->options.comp_type;
+               /* The rest aren't used for format 1 images */
+               header->stripe_unit = 0;
+               header->stripe_count = 0;
+               header->features = 0;
        } else {
-               header->snap_names = NULL;
-               header->snap_sizes = NULL;
+               ceph_put_snap_context(header->snapc);
+               kfree(header->snap_names);
+               kfree(header->snap_sizes);
        }
 
-       header->features = 0;   /* No features support in v1 images */
-       header->obj_order = ondisk->options.order;
-       header->crypt_type = ondisk->options.crypt_type;
-       header->comp_type = ondisk->options.comp_type;
-
-       /* Allocate and fill in the snapshot context */
+       /* The remaining fields always get updated (when we refresh) */
 
        header->image_size = le64_to_cpu(ondisk->image_size);
+       header->snapc = snapc;
+       header->snap_names = snap_names;
+       header->snap_sizes = snap_sizes;
 
-       header->snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
-       if (!header->snapc)
-               goto out_err;
-       header->snapc->seq = le64_to_cpu(ondisk->snap_seq);
-       for (i = 0; i < snap_count; i++)
-               header->snapc->snaps[i] = le64_to_cpu(ondisk->snaps[i].id);
+       /* Make sure mapping size is consistent with header info */
 
-       return 0;
+       if (rbd_dev->spec->snap_id == CEPH_NOSNAP || first_time)
+               if (rbd_dev->mapping.size != header->image_size)
+                       rbd_dev->mapping.size = header->image_size;
+
+       up_write(&rbd_dev->header_rwsem);
 
+       return 0;
+out_2big:
+       ret = -EIO;
 out_err:
-       kfree(header->snap_sizes);
-       header->snap_sizes = NULL;
-       kfree(header->snap_names);
-       header->snap_names = NULL;
-       kfree(header->object_prefix);
-       header->object_prefix = NULL;
+       kfree(snap_sizes);
+       kfree(snap_names);
+       ceph_put_snap_context(snapc);
+       kfree(object_prefix);
 
-       return -ENOMEM;
+       return ret;
 }
 
 static const char *_rbd_dev_v1_snap_name(struct rbd_device *rbd_dev, u32 which)
@@ -819,16 +861,39 @@ static const char *_rbd_dev_v1_snap_name(struct rbd_device *rbd_dev, u32 which)
        return kstrdup(snap_name, GFP_KERNEL);
 }
 
+/*
+ * Snapshot id comparison function for use with qsort()/bsearch().
+ * Note that result is for snapshots in *descending* order.
+ */
+static int snapid_compare_reverse(const void *s1, const void *s2)
+{
+       u64 snap_id1 = *(u64 *)s1;
+       u64 snap_id2 = *(u64 *)s2;
+
+       if (snap_id1 < snap_id2)
+               return 1;
+       return snap_id1 == snap_id2 ? 0 : -1;
+}
+
+/*
+ * Search a snapshot context to see if the given snapshot id is
+ * present.
+ *
+ * Returns the position of the snapshot id in the array if it's found,
+ * or BAD_SNAP_INDEX otherwise.
+ *
+ * Note: The snapshot array is in kept sorted (by the osd) in
+ * reverse order, highest snapshot id first.
+ */
 static u32 rbd_dev_snap_index(struct rbd_device *rbd_dev, u64 snap_id)
 {
        struct ceph_snap_context *snapc = rbd_dev->header.snapc;
-       u32 which;
+       u64 *found;
 
-       for (which = 0; which < snapc->num_snaps; which++)
-               if (snapc->snaps[which] == snap_id)
-                       return which;
+       found = bsearch(&snap_id, &snapc->snaps, snapc->num_snaps,
+                               sizeof (snap_id), snapid_compare_reverse);
 
-       return BAD_SNAP_INDEX;
+       return found ? (u32)(found - &snapc->snaps[0]) : BAD_SNAP_INDEX;
 }
 
 static const char *rbd_dev_v1_snap_name(struct rbd_device *rbd_dev,
@@ -905,20 +970,11 @@ static int rbd_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
 
 static int rbd_dev_mapping_set(struct rbd_device *rbd_dev)
 {
-       const char *snap_name = rbd_dev->spec->snap_name;
-       u64 snap_id;
+       u64 snap_id = rbd_dev->spec->snap_id;
        u64 size = 0;
        u64 features = 0;
        int ret;
 
-       if (strcmp(snap_name, RBD_SNAP_HEAD_NAME)) {
-               snap_id = rbd_snap_id_by_name(rbd_dev, snap_name);
-               if (snap_id == CEPH_NOSNAP)
-                       return -ENOENT;
-       } else {
-               snap_id = CEPH_NOSNAP;
-       }
-
        ret = rbd_snap_size(rbd_dev, snap_id, &size);
        if (ret)
                return ret;
@@ -929,11 +985,6 @@ static int rbd_dev_mapping_set(struct rbd_device *rbd_dev)
        rbd_dev->mapping.size = size;
        rbd_dev->mapping.features = features;
 
-       /* If we are mapping a snapshot it must be marked read-only */
-
-       if (snap_id != CEPH_NOSNAP)
-               rbd_dev->mapping.read_only = true;
-
        return 0;
 }
 
@@ -941,14 +992,6 @@ static void rbd_dev_mapping_clear(struct rbd_device *rbd_dev)
 {
        rbd_dev->mapping.size = 0;
        rbd_dev->mapping.features = 0;
-       rbd_dev->mapping.read_only = true;
-}
-
-static void rbd_dev_clear_mapping(struct rbd_device *rbd_dev)
-{
-       rbd_dev->mapping.size = 0;
-       rbd_dev->mapping.features = 0;
-       rbd_dev->mapping.read_only = true;
 }
 
 static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
@@ -957,7 +1000,7 @@ static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
        u64 segment;
        int ret;
 
-       name = kmalloc(MAX_OBJ_NAME_SIZE + 1, GFP_NOIO);
+       name = kmem_cache_alloc(rbd_segment_name_cache, GFP_NOIO);
        if (!name)
                return NULL;
        segment = offset >> rbd_dev->header.obj_order;
@@ -973,6 +1016,13 @@ static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
        return name;
 }
 
+static void rbd_segment_name_free(const char *name)
+{
+       /* The explicit cast here is needed to drop the const qualifier */
+
+       kmem_cache_free(rbd_segment_name_cache, (void *)name);
+}
+
 static u64 rbd_segment_offset(struct rbd_device *rbd_dev, u64 offset)
 {
        u64 segment_size = (u64) 1 << rbd_dev->header.obj_order;
@@ -1731,11 +1781,16 @@ static struct rbd_obj_request *rbd_obj_request_create(const char *object_name,
        rbd_assert(obj_request_type_valid(type));
 
        size = strlen(object_name) + 1;
-       obj_request = kzalloc(sizeof (*obj_request) + size, GFP_KERNEL);
-       if (!obj_request)
+       name = kmalloc(size, GFP_KERNEL);
+       if (!name)
                return NULL;
 
-       name = (char *)(obj_request + 1);
+       obj_request = kmem_cache_zalloc(rbd_obj_request_cache, GFP_KERNEL);
+       if (!obj_request) {
+               kfree(name);
+               return NULL;
+       }
+
        obj_request->object_name = memcpy(name, object_name, size);
        obj_request->offset = offset;
        obj_request->length = length;
@@ -1781,7 +1836,9 @@ static void rbd_obj_request_destroy(struct kref *kref)
                break;
        }
 
-       kfree(obj_request);
+       kfree(obj_request->object_name);
+       obj_request->object_name = NULL;
+       kmem_cache_free(rbd_obj_request_cache, obj_request);
 }
 
 /*
@@ -1797,7 +1854,7 @@ static struct rbd_img_request *rbd_img_request_create(
 {
        struct rbd_img_request *img_request;
 
-       img_request = kmalloc(sizeof (*img_request), GFP_ATOMIC);
+       img_request = kmem_cache_alloc(rbd_img_request_cache, GFP_ATOMIC);
        if (!img_request)
                return NULL;
 
@@ -1860,7 +1917,7 @@ static void rbd_img_request_destroy(struct kref *kref)
        if (img_request_child_test(img_request))
                rbd_obj_request_put(img_request->obj_request);
 
-       kfree(img_request);
+       kmem_cache_free(rbd_img_request_cache, img_request);
 }
 
 static bool rbd_img_obj_end_request(struct rbd_obj_request *obj_request)
@@ -1998,7 +2055,8 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
                length = rbd_segment_length(rbd_dev, img_offset, resid);
                obj_request = rbd_obj_request_create(object_name,
                                                offset, length, type);
-               kfree(object_name);     /* object request has its own copy */
+               /* object request has its own copy of the object name */
+               rbd_segment_name_free(object_name);
                if (!obj_request)
                        goto out_unwind;
 
@@ -2501,6 +2559,7 @@ static void rbd_img_parent_read_callback(struct rbd_img_request *img_request)
                obj_request->xferred = img_request->xferred;
        }
 out:
+       rbd_img_request_put(img_request);
        rbd_img_obj_request_read_callback(obj_request);
        rbd_obj_request_complete(obj_request);
 }
@@ -2581,6 +2640,7 @@ out:
 static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
 {
        struct rbd_device *rbd_dev = (struct rbd_device *)data;
+       int ret;
 
        if (!rbd_dev)
                return;
@@ -2588,7 +2648,9 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
        dout("%s: \"%s\" notify_id %llu opcode %u\n", __func__,
                rbd_dev->header_name, (unsigned long long)notify_id,
                (unsigned int)opcode);
-       (void)rbd_dev_refresh(rbd_dev);
+       ret = rbd_dev_refresh(rbd_dev);
+       if (ret)
+               rbd_warn(rbd_dev, ": header refresh error (%d)\n", ret);
 
        rbd_obj_notify_ack(rbd_dev, notify_id);
 }
@@ -2824,6 +2886,13 @@ static void rbd_request_fn(struct request_queue *q)
                        goto end_request;       /* Shouldn't happen */
                }
 
+               result = -EIO;
+               if (offset + length > rbd_dev->mapping.size) {
+                       rbd_warn(rbd_dev, "beyond EOD (%llu~%llu > %llu)\n",
+                               offset, length, rbd_dev->mapping.size);
+                       goto end_request;
+               }
+
                result = -ENOMEM;
                img_request = rbd_img_request_create(rbd_dev, offset, length,
                                                        write_request, false);
@@ -2977,17 +3046,11 @@ out:
 }
 
 /*
- * Read the complete header for the given rbd device.
- *
- * Returns a pointer to a dynamically-allocated buffer containing
- * the complete and validated header.  Caller can pass the address
- * of a variable that will be filled in with the version of the
- * header object at the time it was read.
- *
- * Returns a pointer-coded errno if a failure occurs.
+ * Read the complete header for the given rbd device.  On successful
+ * return, the rbd_dev->header field will contain up-to-date
+ * information about the image.
  */
-static struct rbd_image_header_ondisk *
-rbd_dev_v1_header_read(struct rbd_device *rbd_dev)
+static int rbd_dev_v1_header_read(struct rbd_device *rbd_dev)
 {
        struct rbd_image_header_ondisk *ondisk = NULL;
        u32 snap_count = 0;
@@ -3012,22 +3075,22 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev)
                size += names_size;
                ondisk = kmalloc(size, GFP_KERNEL);
                if (!ondisk)
-                       return ERR_PTR(-ENOMEM);
+                       return -ENOMEM;
 
                ret = rbd_obj_read_sync(rbd_dev, rbd_dev->header_name,
                                       0, size, ondisk);
                if (ret < 0)
-                       goto out_err;
+                       goto out;
                if ((size_t)ret < size) {
                        ret = -ENXIO;
                        rbd_warn(rbd_dev, "short header read (want %zd got %d)",
                                size, ret);
-                       goto out_err;
+                       goto out;
                }
                if (!rbd_dev_ondisk_valid(ondisk)) {
                        ret = -ENXIO;
                        rbd_warn(rbd_dev, "invalid header");
-                       goto out_err;
+                       goto out;
                }
 
                names_size = le64_to_cpu(ondisk->snap_names_len);
@@ -3035,103 +3098,65 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev)
                snap_count = le32_to_cpu(ondisk->snap_count);
        } while (snap_count != want_count);
 
-       return ondisk;
-
-out_err:
+       ret = rbd_header_from_disk(rbd_dev, ondisk);
+out:
        kfree(ondisk);
 
-       return ERR_PTR(ret);
+       return ret;
 }
 
 /*
- * reload the ondisk the header
+ * only read the first part of the ondisk header, without the snaps info
  */
-static int rbd_read_header(struct rbd_device *rbd_dev,
-                          struct rbd_image_header *header)
-{
-       struct rbd_image_header_ondisk *ondisk;
-       int ret;
-
-       ondisk = rbd_dev_v1_header_read(rbd_dev);
-       if (IS_ERR(ondisk))
-               return PTR_ERR(ondisk);
-       ret = rbd_header_from_disk(header, ondisk);
-       kfree(ondisk);
-
-       return ret;
-}
-
-static void rbd_update_mapping_size(struct rbd_device *rbd_dev)
+static int rbd_dev_v1_refresh(struct rbd_device *rbd_dev)
 {
-       if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
-               return;
-
-       if (rbd_dev->mapping.size != rbd_dev->header.image_size) {
-               sector_t size;
-
-               rbd_dev->mapping.size = rbd_dev->header.image_size;
-               size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE;
-               dout("setting size to %llu sectors", (unsigned long long)size);
-               set_capacity(rbd_dev->disk, size);
-       }
+       return rbd_dev_v1_header_read(rbd_dev);
 }
 
 /*
- * only read the first part of the ondisk header, without the snaps info
+ * Clear the rbd device's EXISTS flag if the snapshot it's mapped to
+ * has disappeared from the (just updated) snapshot context.
  */
-static int rbd_dev_v1_refresh(struct rbd_device *rbd_dev)
+static void rbd_exists_validate(struct rbd_device *rbd_dev)
 {
-       int ret;
-       struct rbd_image_header h;
-
-       ret = rbd_read_header(rbd_dev, &h);
-       if (ret < 0)
-               return ret;
-
-       down_write(&rbd_dev->header_rwsem);
-
-       /* Update image size, and check for resize of mapped image */
-       rbd_dev->header.image_size = h.image_size;
-       rbd_update_mapping_size(rbd_dev);
-
-       /* rbd_dev->header.object_prefix shouldn't change */
-       kfree(rbd_dev->header.snap_sizes);
-       kfree(rbd_dev->header.snap_names);
-       /* osd requests may still refer to snapc */
-       ceph_put_snap_context(rbd_dev->header.snapc);
+       u64 snap_id;
 
-       rbd_dev->header.image_size = h.image_size;
-       rbd_dev->header.snapc = h.snapc;
-       rbd_dev->header.snap_names = h.snap_names;
-       rbd_dev->header.snap_sizes = h.snap_sizes;
-       /* Free the extra copy of the object prefix */
-       if (strcmp(rbd_dev->header.object_prefix, h.object_prefix))
-               rbd_warn(rbd_dev, "object prefix changed (ignoring)");
-       kfree(h.object_prefix);
+       if (!test_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags))
+               return;
 
-       up_write(&rbd_dev->header_rwsem);
+       snap_id = rbd_dev->spec->snap_id;
+       if (snap_id == CEPH_NOSNAP)
+               return;
 
-       return ret;
+       if (rbd_dev_snap_index(rbd_dev, snap_id) == BAD_SNAP_INDEX)
+               clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
 }
 
 static int rbd_dev_refresh(struct rbd_device *rbd_dev)
 {
-       u64 image_size;
+       u64 mapping_size;
        int ret;
 
        rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
-       image_size = rbd_dev->header.image_size;
+       mapping_size = rbd_dev->mapping.size;
        mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
        if (rbd_dev->image_format == 1)
                ret = rbd_dev_v1_refresh(rbd_dev);
        else
                ret = rbd_dev_v2_refresh(rbd_dev);
+
+       /* If it's a mapped snapshot, validate its EXISTS flag */
+
+       rbd_exists_validate(rbd_dev);
        mutex_unlock(&ctl_mutex);
-       if (ret)
-               rbd_warn(rbd_dev, "got notification but failed to "
-                          " update snaps: %d\n", ret);
-       if (image_size != rbd_dev->header.image_size)
+       if (mapping_size != rbd_dev->mapping.size) {
+               sector_t size;
+
+               size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE;
+               dout("setting size to %llu sectors", (unsigned long long)size);
+               set_capacity(rbd_dev->disk, size);
                revalidate_disk(rbd_dev->disk);
+       }
 
        return ret;
 }
@@ -3335,6 +3360,8 @@ static ssize_t rbd_image_refresh(struct device *dev,
        int ret;
 
        ret = rbd_dev_refresh(rbd_dev);
+       if (ret)
+               rbd_warn(rbd_dev, ": manual header refresh error (%d)\n", ret);
 
        return ret < 0 ? ret : size;
 }
@@ -3934,6 +3961,7 @@ static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev)
        for (i = 0; i < snap_count; i++)
                snapc->snaps[i] = ceph_decode_64(&p);
 
+       ceph_put_snap_context(rbd_dev->header.snapc);
        rbd_dev->header.snapc = snapc;
 
        dout("  snap context seq = %llu, snap_count = %u\n",
@@ -3994,7 +4022,9 @@ static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev)
        ret = rbd_dev_v2_image_size(rbd_dev);
        if (ret)
                goto out;
-       rbd_update_mapping_size(rbd_dev);
+       if (rbd_dev->spec->snap_id == CEPH_NOSNAP)
+               if (rbd_dev->mapping.size != rbd_dev->header.image_size)
+                       rbd_dev->mapping.size = rbd_dev->header.image_size;
 
        ret = rbd_dev_v2_snap_context(rbd_dev);
        dout("rbd_dev_v2_snap_context returned %d\n", ret);
@@ -4439,31 +4469,7 @@ static void rbd_dev_unprobe(struct rbd_device *rbd_dev)
 
 static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
 {
-       int ret;
-
-       /* Populate rbd image metadata */
-
-       ret = rbd_read_header(rbd_dev, &rbd_dev->header);
-       if (ret < 0)
-               goto out_err;
-
-       /* Version 1 images have no parent (no layering) */
-
-       rbd_dev->parent_spec = NULL;
-       rbd_dev->parent_overlap = 0;
-
-       dout("discovered version 1 image, header name is %s\n",
-               rbd_dev->header_name);
-
-       return 0;
-
-out_err:
-       kfree(rbd_dev->header_name);
-       rbd_dev->header_name = NULL;
-       kfree(rbd_dev->spec->image_id);
-       rbd_dev->spec->image_id = NULL;
-
-       return ret;
+       return rbd_dev_v1_header_read(rbd_dev);
 }
 
 static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
@@ -4492,13 +4498,14 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
                ret = rbd_dev_v2_parent_info(rbd_dev);
                if (ret)
                        goto out_err;
-
                /*
-                * Don't print a warning for parent images.  We can
-                * tell this point because we won't know its pool
-                * name yet (just its pool id).
+                * Print a warning if this image has a parent.
+                * Don't print it if the image now being probed
+                * is itself a parent.  We can tell at this point
+                * because we won't know its pool name yet (just its
+                * pool id).
                 */
-               if (rbd_dev->spec->pool_name)
+               if (rbd_dev->parent_spec && rbd_dev->spec->pool_name)
                        rbd_warn(rbd_dev, "WARNING: kernel layering "
                                        "is EXPERIMENTAL!");
        }
@@ -4522,9 +4529,6 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
        if (ret)
                goto out_err;
 
-       dout("discovered version 2 image, header name is %s\n",
-               rbd_dev->header_name);
-
        return 0;
 out_err:
        rbd_dev->parent_overlap = 0;
@@ -4560,7 +4564,7 @@ static int rbd_dev_probe_parent(struct rbd_device *rbd_dev)
        if (!parent)
                goto out_err;
 
-       ret = rbd_dev_image_probe(parent);
+       ret = rbd_dev_image_probe(parent, true);
        if (ret < 0)
                goto out_err;
        rbd_dev->parent = parent;
@@ -4583,10 +4587,6 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 {
        int ret;
 
-       ret = rbd_dev_mapping_set(rbd_dev);
-       if (ret)
-               return ret;
-
        /* generate unique id: find highest unique id, add one */
        rbd_dev_id_get(rbd_dev);
 
@@ -4608,13 +4608,17 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
        if (ret)
                goto err_out_blkdev;
 
-       ret = rbd_bus_add_dev(rbd_dev);
+       ret = rbd_dev_mapping_set(rbd_dev);
        if (ret)
                goto err_out_disk;
+       set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
+
+       ret = rbd_bus_add_dev(rbd_dev);
+       if (ret)
+               goto err_out_mapping;
 
        /* Everything's ready.  Announce the disk to the world. */
 
-       set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
        set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
        add_disk(rbd_dev->disk);
 
@@ -4623,6 +4627,8 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 
        return ret;
 
+err_out_mapping:
+       rbd_dev_mapping_clear(rbd_dev);
 err_out_disk:
        rbd_free_disk(rbd_dev);
 err_out_blkdev:
@@ -4683,7 +4689,7 @@ static void rbd_dev_image_release(struct rbd_device *rbd_dev)
  * device.  For format 2 images this includes determining the image
  * id.
  */
-static int rbd_dev_image_probe(struct rbd_device *rbd_dev)
+static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool read_only)
 {
        int ret;
        int tmp;
@@ -4718,10 +4724,20 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev)
        if (ret)
                goto err_out_probe;
 
+       /* If we are mapping a snapshot it must be marked read-only */
+
+       if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
+               read_only = true;
+       rbd_dev->mapping.read_only = read_only;
+
        ret = rbd_dev_probe_parent(rbd_dev);
-       if (!ret)
-               return 0;
+       if (ret)
+               goto err_out_probe;
+
+       dout("discovered format %u image, header name is %s\n",
+               rbd_dev->image_format, rbd_dev->header_name);
 
+       return 0;
 err_out_probe:
        rbd_dev_unprobe(rbd_dev);
 err_out_watch:
@@ -4751,6 +4767,7 @@ static ssize_t rbd_add(struct bus_type *bus,
        struct rbd_spec *spec = NULL;
        struct rbd_client *rbdc;
        struct ceph_osd_client *osdc;
+       bool read_only;
        int rc = -ENOMEM;
 
        if (!try_module_get(THIS_MODULE))
@@ -4760,6 +4777,9 @@ static ssize_t rbd_add(struct bus_type *bus,
        rc = rbd_add_parse_args(buf, &ceph_opts, &rbd_opts, &spec);
        if (rc < 0)
                goto err_out_module;
+       read_only = rbd_opts->read_only;
+       kfree(rbd_opts);
+       rbd_opts = NULL;        /* done with this */
 
        rbdc = rbd_get_client(ceph_opts);
        if (IS_ERR(rbdc)) {
@@ -4790,11 +4810,7 @@ static ssize_t rbd_add(struct bus_type *bus,
        rbdc = NULL;            /* rbd_dev now owns this */
        spec = NULL;            /* rbd_dev now owns this */
 
-       rbd_dev->mapping.read_only = rbd_opts->read_only;
-       kfree(rbd_opts);
-       rbd_opts = NULL;        /* done with this */
-
-       rc = rbd_dev_image_probe(rbd_dev);
+       rc = rbd_dev_image_probe(rbd_dev, read_only);
        if (rc < 0)
                goto err_out_rbd_dev;
 
@@ -4843,7 +4859,7 @@ static void rbd_dev_device_release(struct device *dev)
 
        rbd_free_disk(rbd_dev);
        clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
-       rbd_dev_clear_mapping(rbd_dev);
+       rbd_dev_mapping_clear(rbd_dev);
        unregister_blkdev(rbd_dev->major, rbd_dev->name);
        rbd_dev->major = 0;
        rbd_dev_id_put(rbd_dev);
@@ -4945,6 +4961,56 @@ static void rbd_sysfs_cleanup(void)
        device_unregister(&rbd_root_dev);
 }
 
+static int rbd_slab_init(void)
+{
+       rbd_assert(!rbd_img_request_cache);
+       rbd_img_request_cache = kmem_cache_create("rbd_img_request",
+                                       sizeof (struct rbd_img_request),
+                                       __alignof__(struct rbd_img_request),
+                                       0, NULL);
+       if (!rbd_img_request_cache)
+               return -ENOMEM;
+
+       rbd_assert(!rbd_obj_request_cache);
+       rbd_obj_request_cache = kmem_cache_create("rbd_obj_request",
+                                       sizeof (struct rbd_obj_request),
+                                       __alignof__(struct rbd_obj_request),
+                                       0, NULL);
+       if (!rbd_obj_request_cache)
+               goto out_err;
+
+       rbd_assert(!rbd_segment_name_cache);
+       rbd_segment_name_cache = kmem_cache_create("rbd_segment_name",
+                                       MAX_OBJ_NAME_SIZE + 1, 1, 0, NULL);
+       if (rbd_segment_name_cache)
+               return 0;
+out_err:
+       if (rbd_obj_request_cache) {
+               kmem_cache_destroy(rbd_obj_request_cache);
+               rbd_obj_request_cache = NULL;
+       }
+
+       kmem_cache_destroy(rbd_img_request_cache);
+       rbd_img_request_cache = NULL;
+
+       return -ENOMEM;
+}
+
+static void rbd_slab_exit(void)
+{
+       rbd_assert(rbd_segment_name_cache);
+       kmem_cache_destroy(rbd_segment_name_cache);
+       rbd_segment_name_cache = NULL;
+
+       rbd_assert(rbd_obj_request_cache);
+       kmem_cache_destroy(rbd_obj_request_cache);
+       rbd_obj_request_cache = NULL;
+
+       rbd_assert(rbd_img_request_cache);
+       kmem_cache_destroy(rbd_img_request_cache);
+       rbd_img_request_cache = NULL;
+}
+
 static int __init rbd_init(void)
 {
        int rc;
@@ -4954,16 +5020,22 @@ static int __init rbd_init(void)
 
                return -EINVAL;
        }
-       rc = rbd_sysfs_init();
+       rc = rbd_slab_init();
        if (rc)
                return rc;
-       pr_info("loaded " RBD_DRV_NAME_LONG "\n");
-       return 0;
+       rc = rbd_sysfs_init();
+       if (rc)
+               rbd_slab_exit();
+       else
+               pr_info("loaded " RBD_DRV_NAME_LONG "\n");
+
+       return rc;
 }
 
 static void __exit rbd_exit(void)
 {
        rbd_sysfs_cleanup();
+       rbd_slab_exit();
 }
 
 module_init(rbd_init);