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Subject[PATCH] f2fs: fix not to write data pages on the page reclaiming path
Date
Even if f2fs_write_data_page is called by the page reclaiming path, we should
not write the page to provide enough free segments for the worst case scenario.
Otherwise, f2fs can face with no free segment while gc is conducted, resulting
in:

------------[ cut here ]------------
kernel BUG at /home/zeus/f2fs_test/src/fs/f2fs/segment.c:565!
RIP: 0010:[<ffffffffa02c3b11>] [<ffffffffa02c3b11>] new_curseg+0x331/0x340 [f2fs]
Call Trace:
allocate_segment_by_default+0x204/0x280 [f2fs]
allocate_data_block+0x108/0x210 [f2fs]
write_data_page+0x8a/0xc0 [f2fs]
do_write_data_page+0xe1/0x2a0 [f2fs]
move_data_page+0x8a/0xf0 [f2fs]
f2fs_gc+0x446/0x970 [f2fs]
f2fs_balance_fs+0xb6/0xd0 [f2fs]
f2fs_write_begin+0x50/0x350 [f2fs]
? unlock_page+0x27/0x30
? unlock_page+0x27/0x30
generic_file_buffered_write+0x10a/0x280
? file_update_time+0xa3/0xf0
__generic_file_aio_write+0x1c8/0x3d0
? generic_file_aio_write+0x52/0xb0
? generic_file_aio_write+0x52/0xb0
generic_file_aio_write+0x65/0xb0
do_sync_write+0x5a/0x90
vfs_write+0xc5/0x1f0
SyS_write+0x55/0xa0
system_call_fastpath+0x16/0x1b

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
---
fs/f2fs/data.c | 40 ++++++++++++++++------------------------
1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b401be7..388a92e 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -805,38 +805,30 @@ static int f2fs_write_data_page(struct page *page,

zero_user_segment(page, offset, PAGE_CACHE_SIZE);
write:
- if (unlikely(sbi->por_doing)) {
- err = AOP_WRITEPAGE_ACTIVATE;
+ if (unlikely(sbi->por_doing))
goto redirty_out;
- }

/* Dentry blocks are controlled by checkpoint */
if (S_ISDIR(inode->i_mode)) {
inode_dec_dirty_dents(inode);
err = do_write_data_page(page, &fio);
- } else {
- f2fs_lock_op(sbi);
-
- if (f2fs_has_inline_data(inode) || f2fs_may_inline(inode)) {
- err = f2fs_write_inline_data(inode, page, offset);
- f2fs_unlock_op(sbi);
- goto out;
- } else {
- err = do_write_data_page(page, &fio);
- }
-
- f2fs_unlock_op(sbi);
- need_balance_fs = true;
+ goto done;
}
- if (err == -ENOENT)
- goto out;
- else if (err)
+
+ if (wbc->for_reclaim && has_not_enough_free_secs(sbi, 0))
goto redirty_out;

- if (wbc->for_reclaim) {
- f2fs_submit_merged_bio(sbi, DATA, WRITE);
- need_balance_fs = false;
- }
+ need_balance_fs = true;
+
+ f2fs_lock_op(sbi);
+ if (f2fs_has_inline_data(inode) || f2fs_may_inline(inode))
+ err = f2fs_write_inline_data(inode, page, offset);
+ else
+ err = do_write_data_page(page, &fio);
+ f2fs_unlock_op(sbi);
+done:
+ if (err && err != -ENOENT)
+ goto redirty_out;

clear_cold_data(page);
out:
@@ -848,7 +840,7 @@ out:
redirty_out:
wbc->pages_skipped++;
set_page_dirty(page);
- return err;
+ return AOP_WRITEPAGE_ACTIVATE;
}

#define MAX_DESIRED_PAGES_WP 4096
--
1.8.4.474.g128a96c


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