Due to deduplication for compressed data, pclusters can be partially
referenced with their prefixes.
Together with the user-space implementation, it enables EROFS
variable-length global compressed data deduplication with rolling
hash.
Link: https://lore.kernel.org/r/20220923014915.4362-1-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
When the user mounts the erofs second times, the decompression thread
may hung. The problem happens due to a sequence of steps like the
following:
1) Task A called z_erofs_load_lzma_config which obtain all of the node
from the z_erofs_lzma_head.
2) At this time, task B called the z_erofs_lzma_decompress and wanted to
get a node. But the z_erofs_lzma_head was empty, the Task B had to
sleep.
3) Task A release nodes and push nodes into the z_erofs_lzma_head. But
task B was still sleeping.
One example report when the hung happens:
task:kworker/u3:1 state:D stack:14384 pid: 86 ppid: 2 flags:0x00004000
Workqueue: erofs_unzipd z_erofs_decompressqueue_work
Call Trace:
<TASK>
__schedule+0x281/0x760
schedule+0x49/0xb0
z_erofs_lzma_decompress+0x4bc/0x580
? cpu_core_flags+0x10/0x10
z_erofs_decompress_pcluster+0x49b/0xba0
? __update_load_avg_se+0x2b0/0x330
? __update_load_avg_se+0x2b0/0x330
? update_load_avg+0x5f/0x690
? update_load_avg+0x5f/0x690
? set_next_entity+0xbd/0x110
? _raw_spin_unlock+0xd/0x20
z_erofs_decompress_queue.isra.0+0x2e/0x50
z_erofs_decompressqueue_work+0x30/0x60
process_one_work+0x1d3/0x3a0
worker_thread+0x45/0x3a0
? process_one_work+0x3a0/0x3a0
kthread+0xe2/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x22/0x30
</TASK>
Signed-off-by: Yuwen Chen <chenyuwen1@meizu.com>
Fixes: 622ceaddb7 ("erofs: lzma compression support")
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220626224041.4288-1-chenyuwen1@meizu.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
To prepare for the upcoming ztailpacking feature, introduce
z_erofs_fixup_insize() and pageofs_in to wrap up the process
to get the exact compressed size via zero padding.
Link: https://lore.kernel.org/r/20211228054604.114518-3-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Currently, ->lru is a way to arrange non-LRU pages and has some
in-kernel users. In order to minimize noticable issues of page
reclaim and cache thrashing under high memory presure, limited
temporary pages were all chained with ->lru and can be reused
during the request. However, it seems that ->lru could be removed
when folio is landing.
Let's use page->private to chain temporary pages for now instead
and transform EROFS formally after the topic of the folio / file
page design is finalized.
Link: https://lore.kernel.org/r/20211022090120.14675-1-hsiangkao@linux.alibaba.com
Cc: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Add MicroLZMA support in order to maximize compression ratios for
specific scenarios. For example, it's useful for low-end embedded
boards and as a secondary algorithm in a file for specific access
patterns.
MicroLZMA is a new container format for raw LZMA1, which was created
by Lasse Collin aiming to minimize old LZMA headers and get rid of
unnecessary EOPM (end of payload marker) as well as to enable
fixed-sized output compression, especially for 4KiB pclusters.
Similar to LZ4, inplace I/O approach is used to minimize runtime
memory footprint when dealing with I/O. Overlapped decompression is
handled with 1) bounced buffer for data under processing or 2) extra
short-lived pages from the on-stack pagepool which will be shared in
the same read request (128KiB for example).
Link: https://lore.kernel.org/r/20211010213145.17462-8-xiang@kernel.org
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
