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btrfs: extent_io: add proper error handling to lock_extent_buffer_for_io()
This function needs some extra checks on locked pages and eb. For error handling we need to unlock locked pages and the eb. There is a rare >0 return value branch, where all pages get locked while write bio is not flushed. Thankfully it's handled by the only caller, btree_write_cache_pages(), as later write_one_eb() call will trigger submit_one_bio(). So there shouldn't be any problem. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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parent
02c6db4f73
commit
2e3c25136a
1 changed files with 22 additions and 5 deletions
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@ -3492,19 +3492,27 @@ void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
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TASK_UNINTERRUPTIBLE);
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}
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/*
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* Lock eb pages and flush the bio if we can't the locks
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*
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* Return 0 if nothing went wrong
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* Return >0 is same as 0, except bio is not submitted
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* Return <0 if something went wrong, no page is locked
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*/
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static noinline_for_stack int
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lock_extent_buffer_for_io(struct extent_buffer *eb,
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struct btrfs_fs_info *fs_info,
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struct extent_page_data *epd)
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{
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int i, num_pages;
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int i, num_pages, failed_page_nr;
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int flush = 0;
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int ret = 0;
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if (!btrfs_try_tree_write_lock(eb)) {
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flush = 1;
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ret = flush_write_bio(epd);
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BUG_ON(ret < 0);
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if (ret < 0)
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return ret;
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flush = 1;
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btrfs_tree_lock(eb);
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}
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@ -3514,7 +3522,8 @@ lock_extent_buffer_for_io(struct extent_buffer *eb,
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return 0;
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if (!flush) {
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ret = flush_write_bio(epd);
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BUG_ON(ret < 0);
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if (ret < 0)
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return ret;
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flush = 1;
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}
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while (1) {
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@ -3556,7 +3565,10 @@ lock_extent_buffer_for_io(struct extent_buffer *eb,
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if (!trylock_page(p)) {
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if (!flush) {
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ret = flush_write_bio(epd);
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BUG_ON(ret < 0);
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if (ret < 0) {
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failed_page_nr = i;
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goto err_unlock;
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}
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flush = 1;
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}
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lock_page(p);
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@ -3564,6 +3576,11 @@ lock_extent_buffer_for_io(struct extent_buffer *eb,
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}
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return ret;
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err_unlock:
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/* Unlock already locked pages */
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for (i = 0; i < failed_page_nr; i++)
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unlock_page(eb->pages[i]);
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return ret;
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}
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static void end_extent_buffer_writeback(struct extent_buffer *eb)
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