7377e85396
There is a potential deadlock between writeback process and a process
performing write_begin() or write_cache_pages() while trying to write
same compress file, but not compressable, as below:
[Process A] - doing checkpoint
[Process B] [Process C]
f2fs_write_cache_pages()
- lock_page() [all pages in cluster, 0-31]
- f2fs_write_multi_pages()
- f2fs_write_raw_pages()
- f2fs_write_single_data_page()
- f2fs_do_write_data_page()
- return -EAGAIN [f2fs_trylock_op() failed]
- unlock_page(page) [e.g., page 0]
- generic_perform_write()
- f2fs_write_begin()
- f2fs_prepare_compress_overwrite()
- prepare_compress_overwrite()
- lock_page() [e.g., page 0]
- lock_page() [e.g., page 1]
- lock_page(page) [e.g., page 0]
Since there is no compress process, it is no longer necessary to hold
locks on every pages in cluster within f2fs_write_raw_pages().
This patch changes f2fs_write_raw_pages() to release all locks first
and then perform write same as the non-compress file in
f2fs_write_cache_pages().
Fixes:
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.. | ||
acl.c | ||
acl.h | ||
checkpoint.c | ||
compress.c | ||
data.c | ||
debug.c | ||
dir.c | ||
extent_cache.c | ||
f2fs.h | ||
file.c | ||
gc.c | ||
gc.h | ||
hash.c | ||
inline.c | ||
inode.c | ||
iostat.c | ||
iostat.h | ||
Kconfig | ||
Makefile | ||
namei.c | ||
node.c | ||
node.h | ||
recovery.c | ||
segment.c | ||
segment.h | ||
shrinker.c | ||
super.c | ||
sysfs.c | ||
verity.c | ||
xattr.c | ||
xattr.h |