On 04.07.2012 15:38, Alexander Block wrote:
> This patch introduces uuids for subvolumes. Each
> subvolume has it's own uuid. In case it was snapshotted,
> it also contains parent_uuid. In case it was received,
> it also contains received_uuid.
>
> It also introduces subvolume ctime/otime/stime/rtime. The
> first two are comparable to the times found in inodes. otime
> is the origin/creation time and ctime is the change time.
> stime/rtime are only valid on received subvolumes.
> stime is the time of the subvolume when it was
> sent. rtime is the time of the subvolume when it was
> received.
>
> Additionally to the times, we have a transid for each
> time. They are updated at the same place as the times.
>
> btrfs receive uses stransid and rtransid to find out
> if a received subvolume changed in the meantime.
>
> If an older kernel mounts a filesystem with the
> extented fields, all fields become invalid. The next
> mount with a new kernel will detect this and reset the
> fields.
>
> Signed-off-by: Alexander Block <ablock84@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/ctree.h | 43 ++++++++++++++++++++++
> fs/btrfs/disk-io.c | 2 +
> fs/btrfs/inode.c | 4 ++
> fs/btrfs/ioctl.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++--
> fs/btrfs/ioctl.h | 13 +++++++
> fs/btrfs/root-tree.c | 92 +++++++++++++++++++++++++++++++++++++++++++---
> fs/btrfs/transaction.c | 17 +++++++++
> 7 files changed, 258 insertions(+), 9 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 8cfde93..2bd5df8 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -709,6 +709,35 @@ struct btrfs_root_item {
> struct btrfs_disk_key drop_progress;
> u8 drop_level;
> u8 level;
> +
> + /*
> + * The following fields appear after subvol_uuids+subvol_times
> + * were introduced.
> + */
> +
> + /*
> + * This generation number is used to test if the new fields are valid
> + * and up to date while reading the root item. Everytime the root item
> + * is written out, the "generation" field is copied into this field. If
> + * anyone ever mounted the fs with an older kernel, we will have
> + * mismatching generation values here and thus must invalidate the
> + * new fields. See btrfs_update_root and btrfs_find_last_root for
> + * details.
> + * the offset of generation_v2 is also used as the start for the memset
> + * when invalidating the fields.
> + */
> + __le64 generation_v2;
> + u8 uuid[BTRFS_UUID_SIZE];
> + u8 parent_uuid[BTRFS_UUID_SIZE];
> + u8 received_uuid[BTRFS_UUID_SIZE];
> + __le64 ctransid; /* updated when an inode changes */
> + __le64 otransid; /* trans when created */
> + __le64 stransid; /* trans when sent. non-zero for received subvol */
> + __le64 rtransid; /* trans when received. non-zero for received subvol */
> + struct btrfs_timespec ctime;
> + struct btrfs_timespec otime;
> + struct btrfs_timespec stime;
> + struct btrfs_timespec rtime;
> } __attribute__ ((__packed__));
>
> /*
> @@ -1416,6 +1445,8 @@ struct btrfs_root {
> dev_t anon_dev;
>
> int force_cow;
> +
> + spinlock_t root_times_lock;
> };
>
> struct btrfs_ioctl_defrag_range_args {
> @@ -2189,6 +2220,16 @@ BTRFS_SETGET_STACK_FUNCS(root_used, struct btrfs_root_item, bytes_used, 64);
> BTRFS_SETGET_STACK_FUNCS(root_limit, struct btrfs_root_item, byte_limit, 64);
> BTRFS_SETGET_STACK_FUNCS(root_last_snapshot, struct btrfs_root_item,
> last_snapshot, 64);
> +BTRFS_SETGET_STACK_FUNCS(root_generation_v2, struct btrfs_root_item,
> + generation_v2, 64);
> +BTRFS_SETGET_STACK_FUNCS(root_ctransid, struct btrfs_root_item,
> + ctransid, 64);
> +BTRFS_SETGET_STACK_FUNCS(root_otransid, struct btrfs_root_item,
> + otransid, 64);
> +BTRFS_SETGET_STACK_FUNCS(root_stransid, struct btrfs_root_item,
> + stransid, 64);
> +BTRFS_SETGET_STACK_FUNCS(root_rtransid, struct btrfs_root_item,
> + rtransid, 64);
>
> static inline bool btrfs_root_readonly(struct btrfs_root *root)
> {
> @@ -2829,6 +2870,8 @@ int btrfs_find_orphan_roots(struct btrfs_root *tree_root);
> void btrfs_set_root_node(struct btrfs_root_item *item,
> struct extent_buffer *node);
> void btrfs_check_and_init_root_item(struct btrfs_root_item *item);
> +void btrfs_update_root_times(struct btrfs_trans_handle *trans,
> + struct btrfs_root *root);
>
> /* dir-item.c */
> int btrfs_insert_dir_item(struct btrfs_trans_handle *trans,
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 7b845ff..d3b49ad 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -1182,6 +1182,8 @@ static void __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
> root->defrag_running = 0;
> root->root_key.objectid = objectid;
> root->anon_dev = 0;
> +
> + spin_lock_init(&root->root_times_lock);
> }
>
> static int __must_check find_and_setup_root(struct btrfs_root *tree_root,
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 139be17..0f6a65d 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -2734,6 +2734,8 @@ noinline int btrfs_update_inode(struct btrfs_trans_handle *trans,
> */
> if (!btrfs_is_free_space_inode(root, inode)
> && root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID) {
> + btrfs_update_root_times(trans, root);
> +
> ret = btrfs_delayed_update_inode(trans, root, inode);
> if (!ret)
> btrfs_set_inode_last_trans(trans, inode);
> @@ -4728,6 +4730,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
> trace_btrfs_inode_new(inode);
> btrfs_set_inode_last_trans(trans, inode);
>
> + btrfs_update_root_times(trans, root);
> +
> return inode;
> fail:
> if (dir)
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 7011871..8d258cb 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -41,6 +41,7 @@
> #include <linux/vmalloc.h>
> #include <linux/slab.h>
> #include <linux/blkdev.h>
> +#include <linux/uuid.h>
> #include "compat.h"
> #include "ctree.h"
> #include "disk-io.h"
> @@ -346,11 +347,13 @@ static noinline int create_subvol(struct btrfs_root *root,
> struct btrfs_root *new_root;
> struct dentry *parent = dentry->d_parent;
> struct inode *dir;
> + struct timespec cur_time = CURRENT_TIME;
> int ret;
> int err;
> u64 objectid;
> u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
> u64 index = 0;
> + uuid_le new_uuid;
>
> ret = btrfs_find_free_objectid(root->fs_info->tree_root, &objectid);
> if (ret)
> @@ -389,8 +392,9 @@ static noinline int create_subvol(struct btrfs_root *root,
> BTRFS_UUID_SIZE);
> btrfs_mark_buffer_dirty(leaf);
>
> + memset(&root_item, 0, sizeof(root_item));
> +
> inode_item = &root_item.inode;
> - memset(inode_item, 0, sizeof(*inode_item));
> inode_item->generation = cpu_to_le64(1);
> inode_item->size = cpu_to_le64(3);
> inode_item->nlink = cpu_to_le32(1);
> @@ -408,8 +412,15 @@ static noinline int create_subvol(struct btrfs_root *root,
> btrfs_set_root_used(&root_item, leaf->len);
> btrfs_set_root_last_snapshot(&root_item, 0);
>
> - memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
> - root_item.drop_level = 0;
> + btrfs_set_root_generation_v2(&root_item,
> + btrfs_root_generation(&root_item));
> + uuid_le_gen(&new_uuid);
> + memcpy(root_item.uuid, new_uuid.b, BTRFS_UUID_SIZE);
> + root_item.otime.sec = cpu_to_le64(cur_time.tv_sec);
> + root_item.otime.nsec = cpu_to_le64(cur_time.tv_nsec);
> + root_item.ctime = root_item.otime;
> + btrfs_set_root_ctransid(&root_item, trans->transid);
> + btrfs_set_root_otransid(&root_item, trans->transid);
>
> btrfs_tree_unlock(leaf);
> free_extent_buffer(leaf);
> @@ -3395,6 +3406,83 @@ out:
> return ret;
> }
>
> +static long btrfs_ioctl_set_received_subvol(struct file *file,
> + void __user *arg)
> +{
> + struct btrfs_ioctl_received_subvol_args *sa = NULL;
> + struct inode *inode = fdentry(file)->d_inode;
> + struct btrfs_root *root = BTRFS_I(inode)->root;
> + struct btrfs_root_item *root_item = &root->root_item;
> + struct btrfs_trans_handle *trans;
> + int ret = 0;
> +
> + ret = mnt_want_write_file(file);
> + if (ret < 0)
> + return ret;
> +
> + down_write(&root->fs_info->subvol_sem);
> +
> + if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + if (btrfs_root_readonly(root)) {
> + ret = -EROFS;
> + goto out;
> + }
> +
> + if (!inode_owner_or_capable(inode)) {
> + ret = -EACCES;
> + goto out;
> + }
> +
> + sa = memdup_user(arg, sizeof(*sa));
> + if (IS_ERR(sa)) {
> + ret = PTR_ERR(sa);
> + sa = NULL;
> + goto out;
> + }
> +
> + trans = btrfs_start_transaction(root, 1);
> + if (IS_ERR(trans)) {
> + ret = PTR_ERR(trans);
> + trans = NULL;
> + goto out;
> + }
> +
> + sa->rtransid = trans->transid;
> + sa->rtime = CURRENT_TIME;
> +
> + memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
> + btrfs_set_root_stransid(root_item, sa->stransid);
> + btrfs_set_root_rtransid(root_item, sa->rtransid);
> + root_item->stime.sec = cpu_to_le64(sa->stime.tv_sec);
> + root_item->stime.nsec = cpu_to_le64(sa->stime.tv_nsec);
> + root_item->rtime.sec = cpu_to_le64(sa->rtime.tv_sec);
> + root_item->rtime.nsec = cpu_to_le64(sa->rtime.tv_nsec);
> +
> + ret = btrfs_update_root(trans, root->fs_info->tree_root,
> + &root->root_key, &root->root_item);
> + if (ret < 0) {
> + goto out;
are you leaking a trans handle here?
> + } else {
> + ret = btrfs_commit_transaction(trans, root);
> + if (ret < 0)
> + goto out;
> + }
> +
> + ret = copy_to_user(arg, sa, sizeof(*sa));
> + if (ret)
> + ret = -EFAULT;
> +
> +out:
> + kfree(sa);
> + up_write(&root->fs_info->subvol_sem);
> + mnt_drop_write_file(file);
> + return ret;
> +}
> +
> long btrfs_ioctl(struct file *file, unsigned int
> cmd, unsigned long arg)
> {
> @@ -3477,6 +3565,8 @@ long btrfs_ioctl(struct file *file, unsigned int
> return btrfs_ioctl_balance_ctl(root, arg);
> case BTRFS_IOC_BALANCE_PROGRESS:
> return btrfs_ioctl_balance_progress(root, argp);
> + case BTRFS_IOC_SET_RECEIVED_SUBVOL:
> + return btrfs_ioctl_set_received_subvol(file, argp);
> case BTRFS_IOC_GET_DEV_STATS:
> return btrfs_ioctl_get_dev_stats(root, argp, 0);
> case BTRFS_IOC_GET_AND_RESET_DEV_STATS:
> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
> index e440aa6..c9e3fac 100644
> --- a/fs/btrfs/ioctl.h
> +++ b/fs/btrfs/ioctl.h
> @@ -295,6 +295,15 @@ struct btrfs_ioctl_get_dev_stats {
> __u64 unused[128 - 2 - BTRFS_DEV_STAT_VALUES_MAX]; /* pad to 1k */
> };
>
> +struct btrfs_ioctl_received_subvol_args {
> + char uuid[BTRFS_UUID_SIZE]; /* in */
> + __u64 stransid; /* in */
> + __u64 rtransid; /* out */
> + struct timespec stime; /* in */
> + struct timespec rtime; /* out */
> + __u64 reserved[16];
What is this reserved used for? I don't see a mechanism that could be
used to signal that there are useful information here, other than
using a different ioctl.
> +};
> +
> #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
> struct btrfs_ioctl_vol_args)
> #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
> @@ -359,6 +368,10 @@ struct btrfs_ioctl_get_dev_stats {
> struct btrfs_ioctl_ino_path_args)
> #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \
> struct btrfs_ioctl_ino_path_args)
> +
> +#define BTRFS_IOC_SET_RECEIVED_SUBVOL _IOWR(BTRFS_IOCTL_MAGIC, 37, \
> + struct btrfs_ioctl_received_subvol_args)
> +
> #define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \
> struct btrfs_ioctl_get_dev_stats)
> #define BTRFS_IOC_GET_AND_RESET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 53, \
> diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
> index 24fb8ce..17d638e 100644
> --- a/fs/btrfs/root-tree.c
> +++ b/fs/btrfs/root-tree.c
> @@ -16,6 +16,7 @@
> * Boston, MA 021110-1307, USA.
> */
>
> +#include <linux/uuid.h>
> #include "ctree.h"
> #include "transaction.h"
> #include "disk-io.h"
> @@ -25,6 +26,9 @@
> * lookup the root with the highest offset for a given objectid. The key we do
> * find is copied into 'key'. If we find something return 0, otherwise 1, < 0
> * on error.
> + * We also check if the root was once mounted with an older kernel. If we detect
> + * this, the new fields coming after 'level' get overwritten with zeros so to
> + * invalidate the fields.
... "This is detected by a mismatch of the 2 generation fields" ... or something
like that.
> */
> int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
> struct btrfs_root_item *item, struct btrfs_key *key)
> @@ -35,6 +39,9 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
> struct extent_buffer *l;
> int ret;
> int slot;
> + int len;
> + int need_reset = 0;
> + uuid_le uuid;
>
> search_key.objectid = objectid;
> search_key.type = BTRFS_ROOT_ITEM_KEY;
> @@ -60,11 +67,36 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
> ret = 1;
> goto out;
> }
> - if (item)
> + if (item) {
> + len = btrfs_item_size_nr(l, slot);
> read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
> - sizeof(*item));
> + min_t(int, len, (int)sizeof(*item)));
> + if (len < sizeof(*item))
> + need_reset = 1;
> + if (!need_reset && btrfs_root_generation(item)
> + != btrfs_root_generation_v2(item)) {
> + if (btrfs_root_generation_v2(item) != 0) {
> + printk(KERN_WARNING "btrfs: mismatching "
> + "generation and generation_v2 "
> + "found in root item. This root "
> + "was probably mounted with an "
> + "older kernel. Resetting all "
> + "new fields.\n");
> + }
> + need_reset = 1;
> + }
> + if (need_reset) {
> + memset(&item->generation_v2, 0,
> + sizeof(*item) - offsetof(struct btrfs_root_item,
> + generation_v2));
> +
> + uuid_le_gen(&uuid);
> + memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
> + }
> + }
> if (key)
> memcpy(key, &found_key, sizeof(found_key));
> +
> ret = 0;
> out:
> btrfs_free_path(path);
> @@ -91,16 +123,15 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
> int ret;
> int slot;
> unsigned long ptr;
> + int old_len;
>
> path = btrfs_alloc_path();
> if (!path)
> return -ENOMEM;
>
> ret = btrfs_search_slot(trans, root, key, path, 0, 1);
> - if (ret < 0) {
> - btrfs_abort_transaction(trans, root, ret);
> - goto out;
> - }
> + if (ret < 0)
> + goto out_abort;
>
> if (ret != 0) {
> btrfs_print_leaf(root, path->nodes[0]);
> @@ -113,11 +144,47 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
> l = path->nodes[0];
> slot = path->slots[0];
> ptr = btrfs_item_ptr_offset(l, slot);
> + old_len = btrfs_item_size_nr(l, slot);
> +
> + /*
> + * If this is the first time we update the root item which originated
> + * from an older kernel, we need to enlarge the item size to make room
> + * for the added fields.
> + */
> + if (old_len < sizeof(*item)) {
> + btrfs_release_path(path);
> + ret = btrfs_search_slot(trans, root, key, path,
> + -1, 1);
> + if (ret < 0)
> + goto out_abort;
> + ret = btrfs_del_item(trans, root, path);
> + if (ret < 0)
> + goto out_abort;
> + btrfs_release_path(path);
> + ret = btrfs_insert_empty_item(trans, root, path,
> + key, sizeof(*item));
> + if (ret < 0)
> + goto out_abort;
> + l = path->nodes[0];
> + slot = path->slots[0];
> + ptr = btrfs_item_ptr_offset(l, slot);
> + }
> +
> + /*
> + * Update generation_v2 so at the next mount we know the new root
> + * fields are valid.
> + */
> + btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
> +
> write_extent_buffer(l, item, ptr, sizeof(*item));
> btrfs_mark_buffer_dirty(path->nodes[0]);
> out:
> btrfs_free_path(path);
> return ret;
> +
> +out_abort:
> + btrfs_abort_transaction(trans, root, ret);
> + goto out;
> }
>
> int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> @@ -454,3 +521,16 @@ void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
> root_item->byte_limit = 0;
> }
> }
> +
> +void btrfs_update_root_times(struct btrfs_trans_handle *trans,
> + struct btrfs_root *root)
> +{
> + struct btrfs_root_item *item = &root->root_item;
> + struct timespec ct = CURRENT_TIME;
> +
> + spin_lock(&root->root_times_lock);
> + item->ctransid = trans->transid;
> + item->ctime.sec = cpu_to_le64(ct.tv_sec);
> + item->ctime.nsec = cpu_to_le64(ct.tv_nsec);
> + spin_unlock(&root->root_times_lock);
> +}
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index b72b068..a21f308 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -22,6 +22,7 @@
> #include <linux/writeback.h>
> #include <linux/pagemap.h>
> #include <linux/blkdev.h>
> +#include <linux/uuid.h>
> #include "ctree.h"
> #include "disk-io.h"
> #include "transaction.h"
> @@ -926,11 +927,13 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
> struct dentry *dentry;
> struct extent_buffer *tmp;
> struct extent_buffer *old;
> + struct timespec cur_time = CURRENT_TIME;
> int ret;
> u64 to_reserve = 0;
> u64 index = 0;
> u64 objectid;
> u64 root_flags;
> + uuid_le new_uuid;
>
> rsv = trans->block_rsv;
>
> @@ -1016,6 +1019,20 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
> root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
> btrfs_set_root_flags(new_root_item, root_flags);
>
> + btrfs_set_root_generation_v2(new_root_item,
> + trans->transid);
> + uuid_le_gen(&new_uuid);
> + memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
> + memcpy(new_root_item->parent_uuid, root->root_item.uuid,
> + BTRFS_UUID_SIZE);
> + new_root_item->otime.sec = cpu_to_le64(cur_time.tv_sec);
> + new_root_item->otime.nsec = cpu_to_le64(cur_time.tv_nsec);
> + btrfs_set_root_otransid(new_root_item, trans->transid);
> + memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
> + memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
> + btrfs_set_root_stransid(new_root_item, 0);
> + btrfs_set_root_rtransid(new_root_item, 0);
> +
> old = btrfs_lock_root_node(root);
> ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
> if (ret) {
--
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