From bb23e37acb2ae9604130c4819fb8ae0f784a3a2b Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Mon, 6 May 2013 09:51:29 -0500 Subject: [PATCH] rbd: refactor rbd_header_from_disk() This rearranges rbd_header_from_disk so that it: - allocates the snapshot context right away - keeps results in local variables, not changing the passed-in header until it's known we'll succeed - does initialization of set-once fields in a header only if they have not already been set The last point is moot at the moment, because rbd_read_header() (the only caller) always supplies a zero-filled header buffer. Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- drivers/block/rbd.c | 127 ++++++++++++++++++++++++++------------------ 1 file changed, 75 insertions(+), 52 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index b0fbc38cc6f0..a3b6bf5e9ae8 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -727,86 +727,109 @@ 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, struct rbd_image_header_ondisk *ondisk) { + 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; - snap_count = le32_to_cpu(ondisk->snap_count); + /* Allocate this now to avoid having to handle failure below */ - 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'; + if (first_time) { + size_t len; + 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; - /* - * 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); - /* Record each snapshot's size */ + /* ...as well as the array of their sizes. */ size = snap_count * sizeof (*header->snap_sizes); - header->snap_sizes = kmalloc(size, GFP_KERNEL); - if (!header->snap_sizes) + snap_sizes = kmalloc(size, GFP_KERNEL); + if (!snap_sizes) goto out_err; - for (i = 0; i < snap_count; i++) - header->snap_sizes[i] = - le64_to_cpu(ondisk->snaps[i].image_size); - } else { - header->snap_names = NULL; - header->snap_sizes = NULL; + + /* + * 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(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); + } } - 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; + /* We won't fail any more, fill in the header */ + + 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; + } - /* 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 = 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); + header->snapc = snapc; + header->snap_names = snap_names; + header->snap_sizes = snap_sizes; 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) -- 2.20.1