btrfs: qgroup: check generation when recording simple quota delta

Simple quotas count extents only from the moment the feature is enabled.
Therefore, if we do something like:

1. create subvol S
2. write F in S
3. enable quotas
4. remove F
5. write G in S

then after 3. and 4. we would expect the simple quota usage of S to be 0
(putting aside some metadata extents that might be written) and after
5., it should be the size of G plus metadata. Therefore, we need to be
able to determine whether a particular quota delta we are processing
predates simple quota enablement.

To do this, store the transaction id when quotas were enabled. In
fs_info for immediate use and in the quota status item to make it
recoverable on mount. When we see a delta, check if the generation of
the extent item is less than that of quota enablement. If so, we should
ignore the delta from this extent.

Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
index fb1c1a1983f29d88be24201141f7e04972d33a95..aa08445356449e5d590598e886f22a2ddf984649 100644 (file)
--- a/fs/btrfs/accessors.h
+++ b/fs/btrfs/accessors.h
@@ -980,6 +980,8 @@ BTRFS_SETGET_FUNCS(qgroup_status_flags, struct btrfs_qgroup_status_item,
                   flags, 64);
 BTRFS_SETGET_FUNCS(qgroup_status_rescan, struct btrfs_qgroup_status_item,
                   rescan, 64);
+BTRFS_SETGET_FUNCS(qgroup_status_enable_gen, struct btrfs_qgroup_status_item,
+                  enable_gen, 64);
 
 /* btrfs_qgroup_info_item */
 BTRFS_SETGET_FUNCS(qgroup_info_generation, struct btrfs_qgroup_info_item,

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 865c74dffe82231fd31108a5a88cc83cb22a9b0a..8372d065aef4cfac7e17e0cae0f9e426e90a1760 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1566,6 +1566,7 @@ static int run_delayed_data_ref(struct btrfs_trans_handle *trans,
                        .rsv_bytes = href->reserved_bytes,
                        .is_data = true,
                        .is_inc = true,
+                       .generation = trans->transid,
                };
 
                if (extent_op)
@@ -1738,6 +1739,7 @@ static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
                        .rsv_bytes = 0,
                        .is_data = false,
                        .is_inc = true,
+                       .generation = trans->transid,
                };
 
                BUG_ON(!extent_op || !extent_op->update_flags);
@@ -3287,6 +3289,7 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
                        .rsv_bytes = 0,
                        .is_data = is_data,
                        .is_inc = false,
+                       .generation = btrfs_extent_generation(leaf, ei),
                };
 
                /* In this branch refs == 1 */
@@ -4924,6 +4927,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
        struct btrfs_squota_delta delta = {
                .root = root_objectid,
                .num_bytes = ins->offset,
+               .generation = trans->transid,
                .rsv_bytes = 0,
                .is_data = true,
                .is_inc = true,

diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index e8fcf34f208a9f7c44d5f4e92c5867d9b58917ba..2bd9bedc70958067f6579bee1cc341a648d17ac9 100644 (file)
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -687,6 +687,7 @@ struct btrfs_fs_info {
        /* Protected by qgroup_rescan_lock */
        bool qgroup_rescan_running;
        u8 qgroup_drop_subtree_thres;
+       u64 qgroup_enable_gen;
 
        /*
         * If this is not 0, then it indicates a serious filesystem error has

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 5b3ad2f150399f5571a0099d5107e5107bd0f1b4..f11f0fc8a9ff53cc9f3b6dddb3e66f3344922dee 100644 (file)
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -369,6 +369,15 @@ static void qgroup_mark_inconsistent(struct btrfs_fs_info *fs_info)
                                  BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING);
 }
 
+static void qgroup_read_enable_gen(struct btrfs_fs_info *fs_info,
+                                  struct extent_buffer *leaf, int slot,
+                                  struct btrfs_qgroup_status_item *ptr)
+{
+       ASSERT(btrfs_fs_incompat(fs_info, SIMPLE_QUOTA));
+       ASSERT(btrfs_item_size(leaf, slot) >= sizeof(*ptr));
+       fs_info->qgroup_enable_gen = btrfs_qgroup_status_enable_gen(leaf, ptr);
+}
+
 /*
  * The full config is read in one go, only called from open_ctree()
  * It doesn't use any locking, as at this point we're still single-threaded
@@ -384,7 +393,6 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info)
        int ret = 0;
        u64 flags = 0;
        u64 rescan_progress = 0;
-       bool simple;
 
        if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_DISABLED)
                return 0;
@@ -437,9 +445,9 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info)
                                goto out;
                        }
                        fs_info->qgroup_flags = btrfs_qgroup_status_flags(l, ptr);
-                       simple = (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE);
-                       if (btrfs_qgroup_status_generation(l, ptr) !=
-                           fs_info->generation && !simple) {
+                       if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE) {
+                               qgroup_read_enable_gen(fs_info, l, slot, ptr);
+                       } else if (btrfs_qgroup_status_generation(l, ptr) != fs_info->generation) {
                                qgroup_mark_inconsistent(fs_info);
                                btrfs_err(fs_info,
                                        "qgroup generation mismatch, marked as inconsistent");
@@ -1103,10 +1111,12 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info,
        btrfs_set_qgroup_status_generation(leaf, ptr, trans->transid);
        btrfs_set_qgroup_status_version(leaf, ptr, BTRFS_QGROUP_STATUS_VERSION);
        fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON;
-       if (simple)
+       if (simple) {
                fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE;
-       else
+               btrfs_set_qgroup_status_enable_gen(leaf, ptr, trans->transid);
+       } else {
                fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
+       }
        btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags &
                                      BTRFS_QGROUP_STATUS_FLAGS_MASK);
        btrfs_set_qgroup_status_rescan(leaf, ptr, 0);
@@ -1210,6 +1220,8 @@ out_add_root:
                goto out_free_path;
        }
 
+       fs_info->qgroup_enable_gen = trans->transid;
+
        mutex_unlock(&fs_info->qgroup_ioctl_lock);
        /*
         * Commit the transaction while not holding qgroup_ioctl_lock, to avoid
@@ -4655,6 +4667,10 @@ int btrfs_record_squota_delta(struct btrfs_fs_info *fs_info,
        if (!is_fstree(root))
                return 0;
 
+       /* If the extent predates enabling quotas, don't count it. */
+       if (delta->generation < fs_info->qgroup_enable_gen)
+               return 0;
+
        spin_lock(&fs_info->qgroup_lock);
        qgroup = find_qgroup_rb(fs_info, root);
        if (!qgroup) {

diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
index 9858244eef20dbc64a139dd3c23ffbe1116fece9..855a4f97876185099db6a188d70c75ace327071f 100644 (file)
--- a/fs/btrfs/qgroup.h
+++ b/fs/btrfs/qgroup.h
@@ -276,6 +276,8 @@ struct btrfs_squota_delta {
        u64 num_bytes;
        /* The number of bytes reserved for this extent. */
        u64 rsv_bytes;
+       /* The generation the extent was created in. */
+       u64 generation;
        /* Whether we are using or freeing the extent. */
        bool is_inc;
        /* Whether the extent is data or metadata. */

diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 8b4def6aee52f0810480a05953c70cf6a4c4d32f..c25fc96145947ed3468aebfbad81d22015f5f239 100644 (file)
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -1277,6 +1277,15 @@ struct btrfs_qgroup_status_item {
         * of the scan. It contains a logical address
         */
        __le64 rescan;
+
+       /*
+        * The generation when quotas were last enabled. Used by simple quotas to
+        * avoid decrementing when freeing an extent that was written before
+        * enable.
+        *
+        * Set only if flags contain BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE.
+        */
+       __le64 enable_gen;
 } __attribute__ ((__packed__));
 
 struct btrfs_qgroup_info_item {