Hi,
When I'm trying XIP on ext2, I find that xip does not work on ext2
with latest kernel.
Reproduce steps:
Compile kernel with following configs:
CONFIG_BLK_DEV_XIP=y
CONFIG_EXT2_FS_XIP=y
And run following commands:
# mke2fs -b 4096 /dev/ram0
# mount -t ext2 -o xip /dev/ram0 /mnt/ramdisk/
# dd if=/dev/zero of=/mnt/ramdisk/test1 bs=1M count=16
And it shows:
dd: writing `/mnt/ramdisk/test1': No space left on device
df also shows /mnt/ramdisk is 100% full. Its default size is 64MB so a
16MB write should only occupy 1/4 capacity.
Criminal commit:
After git bisect, it points to the following commit:
8e3dffc651cb668e1ff4d8b89cc1c3dde7540d3b
Ext2: mark inode dirty after the function dquot_free_block_nodirty is called
Particularly, the following code:
@@ -1412,9 +1415,11 @@ allocated:
*errp = 0;
brelse(bitmap_bh);
- dquot_free_block_nodirty(inode, *count-num);
- mark_inode_dirty(inode);
- *count = num;
+ if (num < *count) {
+ dquot_free_block_nodirty(inode, *count-num);
+ mark_inode_dirty(inode);
+ *count = num;
+ }
return ret_block;
Not mark_inode_dirty() is called only when num is less than *count.
However, I've seen
with the dd command, there is case where num >= *count.
Fix:
I've verified that the following patch fixes the issue:
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 9f9992b..5446a52 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -1406,11 +1406,10 @@ allocated:
*errp = 0;
brelse(bitmap_bh);
- if (num < *count) {
+ if (num <= *count)
dquot_free_block_nodirty(inode, *count-num);
- mark_inode_dirty(inode);
- *count = num;
- }
+ mark_inode_dirty(inode);
+ *count = num;
return ret_block;
io_error:
However, I'm not familiar with ext2 source code and cannot tell if
this is the correct fix. At least it fixes my issue.
Thanks,
Andiry
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