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@@ -3601,6 +3601,68 @@ static void end_extent_buffer_writeback(struct extent_buffer *eb)
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wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
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}
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+static void set_btree_ioerr(struct page *page)
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+{
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+ struct extent_buffer *eb = (struct extent_buffer *)page->private;
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+ struct btrfs_inode *btree_ino = BTRFS_I(eb->fs_info->btree_inode);
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+
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+ SetPageError(page);
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+ if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
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+ return;
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+
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+ /*
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+ * If writeback for a btree extent that doesn't belong to a log tree
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+ * failed, increment the counter transaction->eb_write_errors.
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+ * We do this because while the transaction is running and before it's
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+ * committing (when we call filemap_fdata[write|wait]_range against
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+ * the btree inode), we might have
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+ * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
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+ * returns an error or an error happens during writeback, when we're
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+ * committing the transaction we wouldn't know about it, since the pages
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+ * can be no longer dirty nor marked anymore for writeback (if a
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+ * subsequent modification to the extent buffer didn't happen before the
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+ * transaction commit), which makes filemap_fdata[write|wait]_range not
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+ * able to find the pages tagged with SetPageError at transaction
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+ * commit time. So if this happens we must abort the transaction,
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+ * otherwise we commit a super block with btree roots that point to
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+ * btree nodes/leafs whose content on disk is invalid - either garbage
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+ * or the content of some node/leaf from a past generation that got
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+ * cowed or deleted and is no longer valid.
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+ *
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+ * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
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+ * not be enough - we need to distinguish between log tree extents vs
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+ * non-log tree extents, and the next filemap_fdatawait_range() call
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+ * will catch and clear such errors in the mapping - and that call might
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+ * be from a log sync and not from a transaction commit. Also, checking
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+ * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
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+ * not done and would not be reliable - the eb might have been released
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+ * from memory and reading it back again means that flag would not be
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+ * set (since it's a runtime flag, not persisted on disk).
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+ *
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+ * Using the flags below in the btree inode also makes us achieve the
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+ * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
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+ * writeback for all dirty pages and before filemap_fdatawait_range()
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+ * is called, the writeback for all dirty pages had already finished
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+ * with errors - because we were not using AS_EIO/AS_ENOSPC,
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+ * filemap_fdatawait_range() would return success, as it could not know
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+ * that writeback errors happened (the pages were no longer tagged for
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+ * writeback).
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+ */
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+ switch (eb->log_index) {
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+ case -1:
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+ set_bit(BTRFS_INODE_BTREE_ERR, &btree_ino->runtime_flags);
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+ break;
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+ case 0:
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+ set_bit(BTRFS_INODE_BTREE_LOG1_ERR, &btree_ino->runtime_flags);
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+ break;
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+ case 1:
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+ set_bit(BTRFS_INODE_BTREE_LOG2_ERR, &btree_ino->runtime_flags);
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+ break;
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+ default:
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+ BUG(); /* unexpected, logic error */
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+ }
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+}
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+
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static void end_bio_extent_buffer_writepage(struct bio *bio, int err)
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{
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struct bio_vec *bvec;
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@@ -3614,10 +3676,9 @@ static void end_bio_extent_buffer_writepage(struct bio *bio, int err)
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BUG_ON(!eb);
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done = atomic_dec_and_test(&eb->io_pages);
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- if (err || test_bit(EXTENT_BUFFER_IOERR, &eb->bflags)) {
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- set_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
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+ if (err || test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
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ClearPageUptodate(page);
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- SetPageError(page);
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+ set_btree_ioerr(page);
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}
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end_page_writeback(page);
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@@ -3644,7 +3705,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
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int rw = (epd->sync_io ? WRITE_SYNC : WRITE) | REQ_META;
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int ret = 0;
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- clear_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
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+ clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
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num_pages = num_extent_pages(eb->start, eb->len);
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atomic_set(&eb->io_pages, num_pages);
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if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
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@@ -3661,8 +3722,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
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0, epd->bio_flags, bio_flags);
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epd->bio_flags = bio_flags;
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if (ret) {
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- set_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
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- SetPageError(p);
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+ set_btree_ioerr(p);
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end_page_writeback(p);
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if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
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end_extent_buffer_writeback(eb);
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@@ -5055,7 +5115,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
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goto unlock_exit;
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}
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- clear_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
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+ clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
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eb->read_mirror = 0;
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atomic_set(&eb->io_pages, num_reads);
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for (i = start_i; i < num_pages; i++) {
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Filipe Manana