On 2024/11/6 14:08, Zhiguo Niu wrote:
Chao Yu <c...@kernel.org> 于2024年11月6日周三 10:40写道：
On 2024/11/6 10:26, Zhiguo Niu wrote:
Chao Yu <c...@kernel.org> 于2024年11月6日周三 10:16写道：
On 2024/11/5 19:02, Zhiguo Niu wrote:
Chao Yu <c...@kernel.org> 于2024年11月5日周二 18:39写道：
On 2024/11/5 15:28, Zhiguo Niu wrote:
Chao Yu <c...@kernel.org> 于2024年11月5日周二 15:04写道：
On 2024/11/4 9:56, Zhiguo Niu wrote:
If user give a file size as "length" parameter for fiemap
operations, but if this size is non-block size aligned,
it will show 2 segments fiemap results even this whole file
is contiguous on disk, such as the following results:
./f2fs_io fiemap 0 19034 ylog/analyzer.py
Fiemap: offset = 0 len = 19034
logical addr. physical addr. length flags
0 0000000000000000 0000000020baa000 0000000000004000 00001000
1 0000000000004000 0000000020bae000 0000000000001000 00001001
after this patch:
./f2fs_io fiemap 0 19034 ylog/analyzer.py
Fiemap: offset = 0 len = 19034
logical addr. physical addr. length flags
0 0000000000000000 00000000315f3000 0000000000005000 00001001
Signed-off-by: Zhiguo Niu <zhiguo....@unisoc.com>
---
V2: correct commit msg according to Chao's questions
f2fs_io has been modified for testing, the length for fiemap is
real file size, not block number
---
fs/f2fs/data.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 306b86b0..9fc229d 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1966,8 +1966,8 @@ int f2fs_fiemap(struct inode *inode, struct
fiemap_extent_info *fieinfo,
goto out;
}
- if (bytes_to_blks(inode, len) == 0)
- len = blks_to_bytes(inode, 1);
+ if (len & (blks_to_bytes(inode, 1) - 1))
+ len = round_up(len, blks_to_bytes(inode, 1));
How do you think of getting rid of above alignment for len?
start_blk = bytes_to_blks(inode, start);
last_blk = bytes_to_blks(inode, start + len - 1);
And round up end position w/:
last_blk = bytes_to_blks(inode, round_up(start + len - 1, F2FS_BLKSIZE));
Hi Chao,
I think this will change the current code logic
-------------
if (start_blk > last_blk)
goto out;
-------------
for example, a file with size 19006, but the length from the user is 16384.
before this modification, last_blk = bytes_to_blks(inode, start +
len - 1) = (inode, 16383) = 3
after the first f2fs_map_blocks(). start_blk change to be 4,
after the second f2fs_map_blocks(), fiemap_fill_nex_exten will be
called to fill user parameter and then
will goto out because start_blk > last_blk, then fiemap flow finishes.
but after this modification, last_blk will be 4
will do f2fs_map_blocks() until reach the max_file_blocks(inode)
Yes, you're right, however, w/ this patch, it may change last_blk, e.g.
xfs_io file -c "fiemap -v 0 19006" vs xfs_io file -c "fiemap -v 2 19006"
start_blk and last_blk will be: 0, 4 and 0, 5.
Hi Chao,
yes, but w/o this patch , the original code still has the same situation??
for example
xfs_io file -c "fiemap -v 0 16384" vs xfs_io file -c "fiemap -v 2 16384"
start_blk and last_blk will be: 0, 3 and 0, 4.
For the case "fiemap -v 2 19006", offset is 2, and length is 19006, so
last_offset
is 19008, and last_blk should be 4 rather than 5, right?
hi Chao,
it is right w/o my patch.
And for you case, it calculates last_blk correctly.
So you suggest that "Should we round_up len after start_blk & last_blk
calculation?"
Zhiguo,
Yes, I think alignment of len should not affect calculation of last_blk.
I mean this,
---
fs/f2fs/data.c | 6 +++---
include/linux/f2fs_fs.h | 3 ++-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 7d1bb9518a40..cbbb956f420d 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1967,12 +1967,12 @@ int f2fs_fiemap(struct inode *inode, struct
fiemap_extent_info *fieinfo,
goto out;
}
- if (bytes_to_blks(inode, len) == 0)
- len = blks_to_bytes(inode, 1);
-
start_blk = bytes_to_blks(inode, start);
last_blk = bytes_to_blks(inode, start + len - 1);
+ if (len & F2FS_BLKSIZE_MASK)
+ len = round_up(len, F2FS_BLKSIZE);
+
Hi Chao,
this verion verify pass with my test case.
but there is still another issue in orginal code:
ylog/analyzer.py size = 19034
if I input the following cmd(start/length are both real size, not block number)
/f2fs_io fiemap 2 16384 ylog/analyzer.py
and the results shows:
Fiemap: offset = 2 len = 16384
logical addr. physical addr. length flags
0 0000000000000000 0000000e2ebca000 0000000000004000 00001000
1 0000000000004000 0000000e2ebce000 0000000000001000 00001001
so start_blk/last_blk should be calculate it in the following way?
IIUC, the root cause is f2fs_map_blocks() will truncate size of
returned extent to F2FS_BYTES_TO_BLK(len), so whenever parameter
@len doesn't cover last extent, it triggers this bug.
next:
memset(&map, 0, sizeof(map));
map.m_lblk = start_blk;
map.m_len = F2FS_BYTES_TO_BLK(len); --- limit max size of extent it
founds
map.m_next_pgofs = &next_pgofs;
map.m_seg_type = NO_CHECK_TYPE;
...
ret = f2fs_map_blocks(inode, &map, F2FS_GET_BLOCK_FIEMAP);
xfs_io file -c "fiemap -v 2 16384"
file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..31]: 139272..139303 32 0x1000
1: [32..39]: 139304..139311 8 0x1001
xfs_io file -c "fiemap -v 0 16384"
file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..31]: 139272..139303 32 0x1000
xfs_io file -c "fiemap -v 0 16385"
file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..39]: 139272..139311 40 0x1001
Thoughts?
Thanks,
before:
start_blk = bytes_to_blks(inode, start);
last_blk = bytes_to_blks(inode, start + len - 1);
after:
start_blk = bytes_to_blks(inode, start);
last_blk = start_blk + bytes_to_blks(inode, len - 1);
thanks!
next:
memset(&map, 0, sizeof(map));
map.m_lblk = start_blk;
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index b0b821edfd97..954e8e8344b7 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -24,10 +24,11 @@
#define NEW_ADDR ((block_t)-1) /* used as block_t addresses */
#define COMPRESS_ADDR ((block_t)-2) /* used as compressed data
flag */
+#define F2FS_BLKSIZE_MASK (F2FS_BLKSIZE - 1)
#define F2FS_BYTES_TO_BLK(bytes) ((bytes) >> F2FS_BLKSIZE_BITS)
#define F2FS_BLK_TO_BYTES(blk) ((blk) << F2FS_BLKSIZE_BITS)
#define F2FS_BLK_END_BYTES(blk) (F2FS_BLK_TO_BYTES(blk + 1) -
1)
-#define F2FS_BLK_ALIGN(x) (F2FS_BYTES_TO_BLK((x) +
F2FS_BLKSIZE - 1))
+#define F2FS_BLK_ALIGN(x) (F2FS_BYTES_TO_BLK((x) + F2FS_BLKSIZE -
1))
/* 0, 1(node nid), 2(meta nid) are reserved node id */
#define F2FS_RESERVED_NODE_NUM 3
--
2.40.1
Thanks
Thanks,
but overall last_blk will change loop counts but has not affect on the results.
Should we round_up len after start_blk & last_blk calculation?
I thinks it is ok ,but just a little bit redundant with the following
handling about len.
if (bytes_to_blks(inode, len) == 0)
len = blks_to_bytes(inode, 1);
Based on the above situation,
do you have any other good suggestions? ^^
thanks!
Thanks,
thanks！
Thanks,
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