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Commit 3853368b authored by David Sterba's avatar David Sterba
Browse files

btrfs: preallocate compression workspaces 



Preallocate one workspace for each compression type so we can guarantee
forward progress in the worst case. A failure cannot be a hard error as
we might not use compression at all on the filesystem. If we can't
allocate the workspaces later when need them, it might actually
deadlock, but in such situation the system has effectively not enough
memory to operate properly.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent b7bde417

fs/btrfs/compression.c

+16 −0
Original line number Diff line number Diff line
@@ -761,10 +761,26 @@ void __init btrfs_init_compress(void) 
	int i;



	for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {

		struct list_head *workspace;



		INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);

		spin_lock_init(&btrfs_comp_ws[i].ws_lock);

		atomic_set(&btrfs_comp_ws[i].total_ws, 0);

		init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);



		/*

		 * Preallocate one workspace for each compression type so

		 * we can guarantee forward progress in the worst case

		 */

		workspace = btrfs_compress_op[i]->alloc_workspace();

		if (IS_ERR(workspace)) {

			printk(KERN_WARNING

	"BTRFS: cannot preallocate compression workspace, will try later");

		} else {

			atomic_set(&btrfs_comp_ws[i].total_ws, 1);

			btrfs_comp_ws[i].free_ws = 1;

			list_add(workspace, &btrfs_comp_ws[i].idle_ws);

		}

	}

}