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UPSTREAM: erofs: use sync decompression for atomic contexts only

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Sync decompression was introduced to get rid of additional kworker
scheduling overhead. But there is no such overhead in non-atomic
contexts. Therefore, it should be better to turn off sync decompression
to avoid the current thread waiting in z_erofs_runqueue.

Link: https://lore.kernel.org/r/20210317035448.13921-3-huangjianan@oppo.com
Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Guo Weichao <guoweichao@oppo.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

Bug: 190585249
Change-Id: I7e03053d690b9cda4fe78c0ed0e2fbb0ba188d38
(cherry picked from commit 30048cdac4)
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
This commit is contained in:
Huang Jianan 2021-03-17 11:54:48 +08:00 • committed by Greg Kroah-Hartman
commit 0a24d25f08
3 changed files with 9 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

2
fs/erofs/internal.h
View file

@ -50,6 +50,8 @@ struct erofs_fs_context {
#ifdef CONFIG_EROFS_FS_ZIP
/* current strategy of how to use managed cache */
unsigned char cache_strategy;
/* strategy of sync decompression (false - auto, true - force on) */
bool readahead_sync_decompress;
/* threshold for decompression synchronously */
unsigned int max_sync_decompress_pages;

1
fs/erofs/super.c
View file

@ -200,6 +200,7 @@ static void erofs_default_options(struct erofs_fs_context *ctx)
#ifdef CONFIG_EROFS_FS_ZIP
ctx->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
ctx->max_sync_decompress_pages = 3;
ctx->readahead_sync_decompress = false;
#endif
#ifdef CONFIG_EROFS_FS_XATTR
set_opt(ctx, XATTR_USER);

8
fs/erofs/zdata.c
View file

@ -713,6 +713,8 @@ static void z_erofs_decompressqueue_work(struct work_struct *work);
static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
bool sync, int bios)
{
struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
/* wake up the caller thread for sync decompression */
if (sync) {
unsigned long flags;
@ -726,9 +728,10 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
if (atomic_add_return(bios, &io->pending_bios))
return;
/* Use workqueue decompression for atomic contexts only */
/* Use workqueue and sync decompression for atomic contexts only */
if (in_atomic() || irqs_disabled()) {
queue_work(z_erofs_workqueue, &io->u.work);
sbi->ctx.readahead_sync_decompress = true;
return;
}
z_erofs_decompressqueue_work(&io->u.work);
@ -1343,7 +1346,8 @@ static void z_erofs_readahead(struct readahead_control *rac)
struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
unsigned int nr_pages = readahead_count(rac);
bool sync = (nr_pages <= sbi->ctx.max_sync_decompress_pages);
bool sync = (sbi->ctx.readahead_sync_decompress &&
nr_pages <= sbi->ctx.max_sync_decompress_pages);
struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
struct page *page, *head = NULL;
LIST_HEAD(pagepool);