[PATCH] f2fs: fix out-place-update DIO write

From: Chao Yu
Date: Tue Nov 13 2018 - 01:34:06 EST

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In get_more_blocks(), we may override @create as below code:

create = dio->op == REQ_OP_WRITE;
if (dio->flags & DIO_SKIP_HOLES) {
if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
i_blkbits))
create = 0;
}

But in f2fs_map_blocks(), we only trigger f2fs_balance_fs() if @create
is 1, so in LFS mode, dio overwrite under LFS mode can easily run out
of free segments, result in below panic.

Call Trace:
allocate_segment_by_default+0xa8/0x270 [f2fs]
f2fs_allocate_data_block+0x1ea/0x5c0 [f2fs]
__allocate_data_block+0x306/0x480 [f2fs]
f2fs_map_blocks+0x6f6/0x920 [f2fs]
__get_data_block+0x4f/0xb0 [f2fs]
get_data_block_dio_write+0x50/0x60 [f2fs]
do_blockdev_direct_IO+0xcd5/0x21e0
__blockdev_direct_IO+0x3a/0x3c
f2fs_direct_IO+0x1ff/0x4a0 [f2fs]
generic_file_direct_write+0xd9/0x160
__generic_file_write_iter+0xbb/0x1e0
f2fs_file_write_iter+0xaf/0x220 [f2fs]
__vfs_write+0xd0/0x130
vfs_write+0xb2/0x1b0
SyS_pwrite64+0x69/0xa0
? vtime_user_exit+0x29/0x70
do_syscall_64+0x6e/0x160
entry_SYSCALL64_slow_path+0x25/0x25
RIP: new_curseg+0x36f/0x380 [f2fs] RSP: ffffac570393f7a8

So this patch introduces a parameter map.m_may_create to indicate that
f2fs_map_blocks() is called from write or read path, which can give the
right hint to let f2fs_map_blocks() trigger OPU allocation and call
f2fs_balanc_fs() correctly.

BTW, it disables physical address preallocation for direct IO in
f2fs_preallocate_blocks, which is redundant to OPU allocation of
f2fs_map_blocks.

Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
fs/f2fs/data.c | 42 +++++++++++++++++++++++++++++-------------
fs/f2fs/f2fs.h | 1 +
fs/f2fs/file.c | 3 ++-
3 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 6a78d3f71318..3700e09a748a 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1000,6 +1000,9 @@ int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
return err;
}

+ if (direct_io && allow_outplace_dio(inode, iocb, from))
+ return 0;
+
if (is_inode_flag_set(inode, FI_NO_PREALLOC))
return 0;

@@ -1013,6 +1016,7 @@ int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
map.m_next_pgofs = NULL;
map.m_next_extent = NULL;
map.m_seg_type = NO_CHECK_TYPE;
+ map.m_may_create = true;

if (direct_io) {
map.m_seg_type = f2fs_rw_hint_to_seg_type(iocb->ki_hint);
@@ -1071,7 +1075,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
unsigned int maxblocks = map->m_len;
struct dnode_of_data dn;
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
- int mode = create ? ALLOC_NODE : LOOKUP_NODE;
+ int mode = map->m_may_create ? ALLOC_NODE : LOOKUP_NODE;
pgoff_t pgofs, end_offset, end;
int err = 0, ofs = 1;
unsigned int ofs_in_node, last_ofs_in_node;
@@ -1105,7 +1109,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
}

next_dnode:
- if (create)
+ if (map->m_may_create)
__do_map_lock(sbi, flag, true);

/* When reading holes, we need its node page */
@@ -1142,8 +1146,8 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,

if (is_valid_data_blkaddr(sbi, blkaddr)) {
/* use out-place-update for driect IO under LFS mode */
- if (test_opt(sbi, LFS) && create &&
- flag == F2FS_GET_BLOCK_DIO) {
+ if (test_opt(sbi, LFS) && flag == F2FS_GET_BLOCK_DIO &&
+ map->m_may_create) {
err = __allocate_data_block(&dn, map->m_seg_type);
if (!err)
set_inode_flag(inode, FI_APPEND_WRITE);
@@ -1252,7 +1256,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,

f2fs_put_dnode(&dn);

- if (create) {
+ if (map->m_may_create) {
__do_map_lock(sbi, flag, false);
f2fs_balance_fs(sbi, dn.node_changed);
}
@@ -1278,7 +1282,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
}
f2fs_put_dnode(&dn);
unlock_out:
- if (create) {
+ if (map->m_may_create) {
__do_map_lock(sbi, flag, false);
f2fs_balance_fs(sbi, dn.node_changed);
}
@@ -1314,7 +1318,7 @@ bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len)

static int __get_data_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create, int flag,
- pgoff_t *next_pgofs, int seg_type)
+ pgoff_t *next_pgofs, int seg_type, bool may_write)
{
struct f2fs_map_blocks map;
int err;
@@ -1324,6 +1328,7 @@ static int __get_data_block(struct inode *inode, sector_t iblock,
map.m_next_pgofs = next_pgofs;
map.m_next_extent = NULL;
map.m_seg_type = seg_type;
+ map.m_may_create = may_write;

err = f2fs_map_blocks(inode, &map, create, flag);
if (!err) {
@@ -1340,16 +1345,25 @@ static int get_data_block(struct inode *inode, sector_t iblock,
{
return __get_data_block(inode, iblock, bh_result, create,
flag, next_pgofs,
- NO_CHECK_TYPE);
+ NO_CHECK_TYPE, create);
+}
+
+static int get_data_block_dio_write(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ return __get_data_block(inode, iblock, bh_result, create,
+ F2FS_GET_BLOCK_DIO, NULL,
+ f2fs_rw_hint_to_seg_type(inode->i_write_hint),
+ true);
}

static int get_data_block_dio(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
return __get_data_block(inode, iblock, bh_result, create,
- F2FS_GET_BLOCK_DIO, NULL,
- f2fs_rw_hint_to_seg_type(
- inode->i_write_hint));
+ F2FS_GET_BLOCK_DIO, NULL,
+ f2fs_rw_hint_to_seg_type(inode->i_write_hint),
+ false);
}

static int get_data_block_bmap(struct inode *inode, sector_t iblock,
@@ -1361,7 +1375,7 @@ static int get_data_block_bmap(struct inode *inode, sector_t iblock,

return __get_data_block(inode, iblock, bh_result, create,
F2FS_GET_BLOCK_BMAP, NULL,
- NO_CHECK_TYPE);
+ NO_CHECK_TYPE, create);
}

static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
@@ -1568,6 +1582,7 @@ static int f2fs_mpage_readpages(struct address_space *mapping,
map.m_next_pgofs = NULL;
map.m_next_extent = NULL;
map.m_seg_type = NO_CHECK_TYPE;
+ map.m_may_create = false;

for (; nr_pages; nr_pages--) {
if (pages) {
@@ -2696,7 +2711,8 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
}

err = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
- iter, get_data_block_dio, NULL, f2fs_dio_submit_bio,
+ iter, rw == WRITE ? get_data_block_dio_write :
+ get_data_block_dio, NULL, f2fs_dio_submit_bio,
DIO_LOCKING | DIO_SKIP_HOLES);

if (do_opu)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 413e9be4e607..13cf9c62a126 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -596,6 +596,7 @@ struct f2fs_map_blocks {
pgoff_t *m_next_pgofs; /* point next possible non-hole pgofs */
pgoff_t *m_next_extent; /* point to next possible extent */
int m_seg_type;
+ bool m_may_create; /* indicate it is from write path */
};

/* for flag in get_data_block */
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 1e168f70d774..5d369b4f5dab 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1499,7 +1499,8 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
{
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
struct f2fs_map_blocks map = { .m_next_pgofs = NULL,
- .m_next_extent = NULL, .m_seg_type = NO_CHECK_TYPE };
+ .m_next_extent = NULL, .m_seg_type = NO_CHECK_TYPE,
+ .m_may_create = true };
pgoff_t pg_end;
loff_t new_size = i_size_read(inode);
loff_t off_end;
--
2.18.0.rc1

Next message: Adeodato SimÃ: "[PATCH] net/9p: include trans_common.h to fix missing prototype warning."
Previous message: Arun KS: "[PATCH v5 0/4] mm: convert totalram_pages, totalhigh_pages and managed pages to atomic"
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