From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/fs/btrfs/reada.c | 130 +++++++++++++++++++++++++++++++++++-------
1 files changed, 107 insertions(+), 23 deletions(-)
diff --git a/kernel/fs/btrfs/reada.c b/kernel/fs/btrfs/reada.c
index 368c349..d9a166e 100644
--- a/kernel/fs/btrfs/reada.c
+++ b/kernel/fs/btrfs/reada.c
@@ -14,6 +14,7 @@
#include "disk-io.h"
#include "transaction.h"
#include "dev-replace.h"
+#include "block-group.h"
#undef DEBUG
@@ -226,7 +227,7 @@
struct btrfs_fs_info *fs_info = dev->fs_info;
int ret;
struct reada_zone *zone;
- struct btrfs_block_group_cache *cache = NULL;
+ struct btrfs_block_group *cache = NULL;
u64 start;
u64 end;
int i;
@@ -247,8 +248,8 @@
if (!cache)
return NULL;
- start = cache->key.objectid;
- end = start + cache->key.offset - 1;
+ start = cache->start;
+ end = start + cache->length - 1;
btrfs_put_block_group(cache);
zone = kzalloc(sizeof(*zone), GFP_KERNEL);
@@ -376,26 +377,28 @@
goto error;
}
+ /* Insert extent in reada tree + all per-device trees, all or nothing */
+ down_read(&fs_info->dev_replace.rwsem);
ret = radix_tree_preload(GFP_KERNEL);
- if (ret)
+ if (ret) {
+ up_read(&fs_info->dev_replace.rwsem);
goto error;
+ }
- /* insert extent in reada_tree + all per-device trees, all or nothing */
- btrfs_dev_replace_read_lock(&fs_info->dev_replace);
spin_lock(&fs_info->reada_lock);
ret = radix_tree_insert(&fs_info->reada_tree, index, re);
if (ret == -EEXIST) {
re_exist = radix_tree_lookup(&fs_info->reada_tree, index);
re_exist->refcnt++;
spin_unlock(&fs_info->reada_lock);
- btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
radix_tree_preload_end();
+ up_read(&fs_info->dev_replace.rwsem);
goto error;
}
if (ret) {
spin_unlock(&fs_info->reada_lock);
- btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
radix_tree_preload_end();
+ up_read(&fs_info->dev_replace.rwsem);
goto error;
}
radix_tree_preload_end();
@@ -418,6 +421,9 @@
if (!dev->bdev)
continue;
+ if (test_bit(BTRFS_DEV_STATE_NO_READA, &dev->dev_state))
+ continue;
+
if (dev_replace_is_ongoing &&
dev == fs_info->dev_replace.tgtdev) {
/*
@@ -437,7 +443,7 @@
}
radix_tree_delete(&fs_info->reada_tree, index);
spin_unlock(&fs_info->reada_lock);
- btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
+ up_read(&fs_info->dev_replace.rwsem);
goto error;
}
have_zone = 1;
@@ -445,7 +451,7 @@
if (!have_zone)
radix_tree_delete(&fs_info->reada_tree, index);
spin_unlock(&fs_info->reada_lock);
- btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
+ up_read(&fs_info->dev_replace.rwsem);
if (!have_zone)
goto error;
@@ -638,6 +644,35 @@
return 1;
}
+static int reada_tree_block_flagged(struct btrfs_fs_info *fs_info, u64 bytenr,
+ int mirror_num, struct extent_buffer **eb)
+{
+ struct extent_buffer *buf = NULL;
+ int ret;
+
+ buf = btrfs_find_create_tree_block(fs_info, bytenr);
+ if (IS_ERR(buf))
+ return 0;
+
+ set_bit(EXTENT_BUFFER_READAHEAD, &buf->bflags);
+
+ ret = read_extent_buffer_pages(buf, WAIT_PAGE_LOCK, mirror_num);
+ if (ret) {
+ free_extent_buffer_stale(buf);
+ return ret;
+ }
+
+ if (test_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags)) {
+ free_extent_buffer_stale(buf);
+ return -EIO;
+ } else if (extent_buffer_uptodate(buf)) {
+ *eb = buf;
+ } else {
+ free_extent_buffer(buf);
+ }
+ return 0;
+}
+
static int reada_start_machine_dev(struct btrfs_device *dev)
{
struct btrfs_fs_info *fs_info = dev->fs_info;
@@ -737,31 +772,39 @@
kfree(rmw);
}
-static void __reada_start_machine(struct btrfs_fs_info *fs_info)
+/* Try to start up to 10k READA requests for a group of devices */
+static int reada_start_for_fsdevs(struct btrfs_fs_devices *fs_devices)
{
- struct btrfs_device *device;
- struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
u64 enqueued;
u64 total = 0;
- int i;
+ struct btrfs_device *device;
-again:
do {
enqueued = 0;
- mutex_lock(&fs_devices->device_list_mutex);
list_for_each_entry(device, &fs_devices->devices, dev_list) {
if (atomic_read(&device->reada_in_flight) <
MAX_IN_FLIGHT)
enqueued += reada_start_machine_dev(device);
}
- mutex_unlock(&fs_devices->device_list_mutex);
total += enqueued;
} while (enqueued && total < 10000);
- if (fs_devices->seed) {
- fs_devices = fs_devices->seed;
- goto again;
- }
+ return total;
+}
+
+static void __reada_start_machine(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_fs_devices *fs_devices = fs_info->fs_devices, *seed_devs;
+ int i;
+ u64 enqueued = 0;
+
+ mutex_lock(&fs_devices->device_list_mutex);
+
+ enqueued += reada_start_for_fsdevs(fs_devices);
+ list_for_each_entry(seed_devs, &fs_devices->seed_list, seed_list)
+ enqueued += reada_start_for_fsdevs(seed_devs);
+
+ mutex_unlock(&fs_devices->device_list_mutex);
if (enqueued == 0)
return;
@@ -789,8 +832,7 @@
/* FIXME we cannot handle this properly right now */
BUG();
}
- btrfs_init_work(&rmw->work, btrfs_readahead_helper,
- reada_start_machine_worker, NULL, NULL);
+ btrfs_init_work(&rmw->work, reada_start_machine_worker, NULL, NULL);
rmw->fs_info = fs_info;
btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
@@ -983,3 +1025,45 @@
kref_put(&rc->refcnt, reada_control_release);
}
+
+/*
+ * Before removing a device (device replace or device remove ioctls), call this
+ * function to wait for all existing readahead requests on the device and to
+ * make sure no one queues more readahead requests for the device.
+ *
+ * Must be called without holding neither the device list mutex nor the device
+ * replace semaphore, otherwise it will deadlock.
+ */
+void btrfs_reada_remove_dev(struct btrfs_device *dev)
+{
+ struct btrfs_fs_info *fs_info = dev->fs_info;
+
+ /* Serialize with readahead extent creation at reada_find_extent(). */
+ spin_lock(&fs_info->reada_lock);
+ set_bit(BTRFS_DEV_STATE_NO_READA, &dev->dev_state);
+ spin_unlock(&fs_info->reada_lock);
+
+ /*
+ * There might be readahead requests added to the radix trees which
+ * were not yet added to the readahead work queue. We need to start
+ * them and wait for their completion, otherwise we can end up with
+ * use-after-free problems when dropping the last reference on the
+ * readahead extents and their zones, as they need to access the
+ * device structure.
+ */
+ reada_start_machine(fs_info);
+ btrfs_flush_workqueue(fs_info->readahead_workers);
+}
+
+/*
+ * If when removing a device (device replace or device remove ioctls) an error
+ * happens after calling btrfs_reada_remove_dev(), call this to undo what that
+ * function did. This is safe to call even if btrfs_reada_remove_dev() was not
+ * called before.
+ */
+void btrfs_reada_undo_remove_dev(struct btrfs_device *dev)
+{
+ spin_lock(&dev->fs_info->reada_lock);
+ clear_bit(BTRFS_DEV_STATE_NO_READA, &dev->dev_state);
+ spin_unlock(&dev->fs_info->reada_lock);
+}
--
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