From 3853368b95f27d9bdaf9e15bc1e11753f11e3c43 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Wed, 27 Apr 2016 02:55:15 +0200 Subject: [PATCH] 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: David Sterba --- fs/btrfs/compression.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 4d5cd9624bb3..38c058bcf359 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -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); + } } } -- 2.20.1