From b7bde4178a61a6855e1afebb60db4358dbbb6830 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Wed, 27 Apr 2016 02:15:15 +0200 Subject: [PATCH] btrfs: rename and document compression workspace members The names are confusing, pick more fitting names and add comments. Signed-off-by: David Sterba --- fs/btrfs/compression.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index ff61a41ac90b..4d5cd9624bb3 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -743,8 +743,11 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, static struct { struct list_head idle_ws; spinlock_t ws_lock; - int num_ws; - atomic_t alloc_ws; + /* Number of free workspaces */ + int free_ws; + /* Total number of allocated workspaces */ + atomic_t total_ws; + /* Waiters for a free workspace */ wait_queue_head_t ws_wait; } btrfs_comp_ws[BTRFS_COMPRESS_TYPES]; @@ -760,7 +763,7 @@ void __init btrfs_init_compress(void) for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) { INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws); spin_lock_init(&btrfs_comp_ws[i].ws_lock); - atomic_set(&btrfs_comp_ws[i].alloc_ws, 0); + atomic_set(&btrfs_comp_ws[i].total_ws, 0); init_waitqueue_head(&btrfs_comp_ws[i].ws_wait); } } @@ -777,35 +780,35 @@ static struct list_head *find_workspace(int type) struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws; spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock; - atomic_t *alloc_ws = &btrfs_comp_ws[idx].alloc_ws; + atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws; wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait; - int *num_ws = &btrfs_comp_ws[idx].num_ws; + int *free_ws = &btrfs_comp_ws[idx].free_ws; again: spin_lock(ws_lock); if (!list_empty(idle_ws)) { workspace = idle_ws->next; list_del(workspace); - (*num_ws)--; + (*free_ws)--; spin_unlock(ws_lock); return workspace; } - if (atomic_read(alloc_ws) > cpus) { + if (atomic_read(total_ws) > cpus) { DEFINE_WAIT(wait); spin_unlock(ws_lock); prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE); - if (atomic_read(alloc_ws) > cpus && !*num_ws) + if (atomic_read(total_ws) > cpus && !*free_ws) schedule(); finish_wait(ws_wait, &wait); goto again; } - atomic_inc(alloc_ws); + atomic_inc(total_ws); spin_unlock(ws_lock); workspace = btrfs_compress_op[idx]->alloc_workspace(); if (IS_ERR(workspace)) { - atomic_dec(alloc_ws); + atomic_dec(total_ws); wake_up(ws_wait); } return workspace; @@ -820,21 +823,21 @@ static void free_workspace(int type, struct list_head *workspace) int idx = type - 1; struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws; spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock; - atomic_t *alloc_ws = &btrfs_comp_ws[idx].alloc_ws; + atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws; wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait; - int *num_ws = &btrfs_comp_ws[idx].num_ws; + int *free_ws = &btrfs_comp_ws[idx].free_ws; spin_lock(ws_lock); - if (*num_ws < num_online_cpus()) { + if (*free_ws < num_online_cpus()) { list_add(workspace, idle_ws); - (*num_ws)++; + (*free_ws)++; spin_unlock(ws_lock); goto wake; } spin_unlock(ws_lock); btrfs_compress_op[idx]->free_workspace(workspace); - atomic_dec(alloc_ws); + atomic_dec(total_ws); wake: /* * Make sure counter is updated before we wake up waiters. @@ -857,7 +860,7 @@ static void free_workspaces(void) workspace = btrfs_comp_ws[i].idle_ws.next; list_del(workspace); btrfs_compress_op[i]->free_workspace(workspace); - atomic_dec(&btrfs_comp_ws[i].alloc_ws); + atomic_dec(&btrfs_comp_ws[i].total_ws); } } } -- 2.45.2