This removes a FIXME comment and introduces the first part of nodatasum
fixup: It gets the corresponding inode for a logical address and triggers a
regular readpage for the corrupted sector.
Once we have on-the-fly error correction our error will be automatically
corrected. The correction code is expected to clear the newly introduced
EXTENT_DAMAGED flag, making scrub report that error as "corrected" instead
of "uncorrectable" eventually.
Signed-off-by: Jan Schmidt <list.bt...@jan-o-sch.net>
---
fs/btrfs/extent_io.h | 1 +
fs/btrfs/scrub.c | 185 +++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 178 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 2fef77f..906ea42 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -17,6 +17,7 @@
#define EXTENT_NODATASUM (1 << 10)
#define EXTENT_DO_ACCOUNTING (1 << 11)
#define EXTENT_FIRST_DELALLOC (1 << 12)
+#define EXTENT_DAMAGED (1 << 13)
#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
#define EXTENT_CTLBITS (EXTENT_DO_ACCOUNTING | EXTENT_FIRST_DELALLOC)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index de918ff..211606f 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -28,6 +28,7 @@
#include "volumes.h"
#include "disk-io.h"
#include "ordered-data.h"
+#include "transaction.h"
#include "backref.h"
/*
@@ -95,6 +96,7 @@ struct scrub_dev {
int first_free;
int curr;
atomic_t in_flight;
+ atomic_t fixup_cnt;
spinlock_t list_lock;
wait_queue_head_t list_wait;
u16 csum_size;
@@ -108,6 +110,14 @@ struct scrub_dev {
spinlock_t stat_lock;
};
+struct scrub_fixup_nodatasum {
+ struct scrub_dev *sdev;
+ u64 logical;
+ struct btrfs_root *root;
+ struct btrfs_work work;
+ int mirror_num;
+};
+
struct scrub_warning {
struct btrfs_path *path;
u64 extent_item_size;
@@ -196,12 +206,13 @@ struct scrub_dev *scrub_setup_dev(struct btrfs_device
*dev)
if (i != SCRUB_BIOS_PER_DEV-1)
sdev->bios[i]->next_free = i + 1;
- else
+ else
sdev->bios[i]->next_free = -1;
}
sdev->first_free = 0;
sdev->curr = -1;
atomic_set(&sdev->in_flight, 0);
+ atomic_set(&sdev->fixup_cnt, 0);
atomic_set(&sdev->cancel_req, 0);
sdev->csum_size = btrfs_super_csum_size(&fs_info->super_copy);
INIT_LIST_HEAD(&sdev->csum_list);
@@ -216,7 +227,7 @@ nomem:
return ERR_PTR(-ENOMEM);
}
-static int scrub_print_warning_inode(u64 inum, loff_t offset, void *ctx)
+static int scrub_print_warning_inode(u64 inum, u64 offset, void *ctx)
{
u64 isize;
int ret;
@@ -282,7 +293,7 @@ static void scrub_print_warning(const char *errstr, struct
scrub_bio *sbio,
u8 ref_level;
unsigned long ptr = 0;
const int bufsize = 4096;
- loff_t extent_item_offset;
+ u64 extent_item_offset;
path = btrfs_alloc_path();
@@ -332,6 +343,144 @@ out:
kfree(swarn.msg_buf);
}
+static int scrub_fixup_readpage(u64 inum, u64 offset, void *ctx)
+{
+ struct page *page;
+ unsigned long index;
+ struct scrub_fixup_nodatasum *fixup = ctx;
+ int ret;
+ int corrected;
+ struct btrfs_key key;
+ struct inode *inode;
+ u64 end = offset + PAGE_SIZE - 1;
+
+ key.type = BTRFS_INODE_ITEM_KEY;
+ key.objectid = inum;
+ key.offset = 0;
+ inode = btrfs_iget(fixup->root->fs_info->sb, &key,
+ fixup->root->fs_info->fs_root, NULL);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+
+ ret = set_extent_bit(&BTRFS_I(inode)->io_tree, offset, end,
+ EXTENT_DAMAGED, 0, NULL, NULL, GFP_NOFS);
+
+ /* set_extent_bit should either succeed or give proper error */
+ WARN_ON(ret > 0);
+ if (ret)
+ return ret < 0 ? ret : -EFAULT;
+
+ index = offset >> PAGE_CACHE_SHIFT;
+
+ page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
+ if (!page)
+ return -ENOMEM;
+
+ ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
+ btrfs_get_extent, fixup->mirror_num);
+ wait_on_page_locked(page);
+ corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset, end,
+ EXTENT_DAMAGED, 0, NULL);
+
+ if (corrected)
+ WARN_ON(!PageUptodate(page));
+ else
+ clear_extent_bit(&BTRFS_I(inode)->io_tree, offset, end,
+ EXTENT_DAMAGED, 0, 0, NULL, GFP_NOFS);
+
+ put_page(page);
+ iput(inode);
+
+ if (ret < 0)
+ return ret;
+
+ if (ret == 0 && corrected) {
+ /*
+ * we only need to call readpage for one of the inodes belonging
+ * to this extent. so make iterate_extent_inodes stop
+ */
+ return 1;
+ }
+
+ return -EIO;
+}
+
+static void scrub_fixup_nodatasum(struct btrfs_work *work)
+{
+ int ret;
+ struct scrub_fixup_nodatasum *fixup;
+ struct scrub_dev *sdev;
+ struct btrfs_trans_handle *trans = NULL;
+ struct btrfs_fs_info *fs_info;
+ struct btrfs_path *path;
+ int uncorrectable = 0;
+
+ fixup = container_of(work, struct scrub_fixup_nodatasum, work);
+ sdev = fixup->sdev;
+ fs_info = fixup->root->fs_info;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ spin_lock(&sdev->stat_lock);
+ ++sdev->stat.malloc_errors;
+ spin_unlock(&sdev->stat_lock);
+ uncorrectable = 1;
+ goto out;
+ }
+
+ trans = btrfs_join_transaction(fixup->root);
+ if (IS_ERR(trans)) {
+ uncorrectable = 1;
+ goto out;
+ }
+
+ /*
+ * the idea is to trigger a regular read through the standard path. we
+ * read a page from the (failed) logical address by specifying the
+ * corresponding copynum of the failed sector. thus, that readpage is
+ * expected to fail.
+ * that is the point where on-the-fly error correction will kick in
+ * (once it's finished) and rewrite the failed sector if a good copy
+ * can be found.
+ */
+ ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
+ path, scrub_fixup_readpage,
+ fixup);
+ if (ret < 0) {
+ uncorrectable = 1;
+ goto out;
+ }
+ WARN_ON(ret != 1);
+
+ spin_lock(&sdev->stat_lock);
+ ++sdev->stat.corrected_errors;
+ spin_unlock(&sdev->stat_lock);
+
+out:
+ if (trans && !IS_ERR(trans))
+ btrfs_end_transaction(trans, fixup->root);
+ if (uncorrectable) {
+ spin_lock(&sdev->stat_lock);
+ ++sdev->stat.uncorrectable_errors;
+ spin_unlock(&sdev->stat_lock);
+ printk_ratelimited(KERN_ERR "btrfs: unable to fixup "
+ "(nodatasum) error at logical %llu\n",
+ fixup->logical);
+ }
+
+ btrfs_free_path(path);
+ kfree(fixup);
+
+ /* see caller why we're pretending to be paused in the scrub counters */
+ mutex_lock(&fs_info->scrub_lock);
+ atomic_dec(&fs_info->scrubs_running);
+ atomic_dec(&fs_info->scrubs_paused);
+ mutex_unlock(&fs_info->scrub_lock);
+ atomic_dec(&sdev->fixup_cnt);
+ wake_up(&fs_info->scrub_pause_wait);
+ wake_up(&sdev->list_wait);
+}
+
/*
* scrub_recheck_error gets called when either verification of the page
* failed or the bio failed to read, e.g. with EIO. In the latter case,
@@ -402,6 +551,7 @@ static void scrub_fixup(struct scrub_bio *sbio, int ix)
struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
struct btrfs_multi_bio *multi = NULL;
+ struct scrub_fixup_nodatasum *fixup;
u64 logical = sbio->logical + ix * PAGE_SIZE;
u64 length;
int i;
@@ -410,12 +560,30 @@ static void scrub_fixup(struct scrub_bio *sbio, int ix)
if ((sbio->spag[ix].flags & BTRFS_EXTENT_FLAG_DATA) &&
(sbio->spag[ix].have_csum == 0)) {
+ fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
+ if (!fixup)
+ goto uncorrectable;
+ fixup->sdev = sdev;
+ fixup->logical = logical;
+ fixup->root = fs_info->extent_root;
+ fixup->mirror_num = sbio->spag[ix].mirror_num;
/*
- * nodatasum, don't try to fix anything
- * FIXME: we can do better, open the inode and trigger a
- * writeback
+ * increment scrubs_running to prevent cancel requests from
+ * completing as long as a fixup worker is running. we must also
+ * increment scrubs_paused to prevent deadlocking on pause
+ * requests used for transactions commits (as the worker uses a
+ * transaction context). it is safe to regard the fixup worker
+ * as paused for all matters practical. effectively, we only
+ * avoid cancellation requests from completing.
*/
- goto uncorrectable;
+ mutex_lock(&fs_info->scrub_lock);
+ atomic_inc(&fs_info->scrubs_running);
+ atomic_inc(&fs_info->scrubs_paused);
+ mutex_unlock(&fs_info->scrub_lock);
+ atomic_inc(&sdev->fixup_cnt);
+ fixup->work.func = scrub_fixup_nodatasum;
+ btrfs_queue_worker(&fs_info->scrub_workers, &fixup->work);
+ return;
}
length = PAGE_SIZE;
@@ -1405,7 +1573,8 @@ int btrfs_scrub_dev(struct btrfs_root *root, u64 devid,
u64 start, u64 end,
if (!ret)
ret = scrub_enumerate_chunks(sdev, start, end);
- wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
+ wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0 &&
+ atomic_read(&sdev->fixup_cnt) == 0);
atomic_dec(&fs_info->scrubs_running);
wake_up(&fs_info->scrub_pause_wait);
--
1.7.3.4
--
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