f2fs: support atomic writes
This patch introduces a very limited functionality for atomic write support.
In order to support atomic write, this patch adds two ioctls:
o F2FS_IOC_START_ATOMIC_WRITE
o F2FS_IOC_COMMIT_ATOMIC_WRITE
The database engine should be aware of the following sequence.
1. open
-> ioctl(F2FS_IOC_START_ATOMIC_WRITE);
2. writes
: all the written data will be treated as atomic pages.
3. commit
-> ioctl(F2FS_IOC_COMMIT_ATOMIC_WRITE);
: this flushes all the data blocks to the disk, which will be shown all or
nothing by f2fs recovery procedure.
4. repeat to #2.
The IO pattens should be:
,- START_ATOMIC_WRITE ,- COMMIT_ATOMIC_WRITE
CP | D D D D D D | FSYNC | D D D D | FSYNC ...
`- COMMIT_ATOMIC_WRITE
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index afb7362..2495bec 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -175,6 +175,11 @@
void (*allocate_segment)(struct f2fs_sb_info *, int, bool);
};
+struct inmem_pages {
+ struct list_head list;
+ struct page *page;
+};
+
struct sit_info {
const struct segment_allocation *s_ops;
@@ -504,7 +509,7 @@
unsigned int policy = SM_I(sbi)->ipu_policy;
/* IPU can be done only for the user data */
- if (S_ISDIR(inode->i_mode))
+ if (S_ISDIR(inode->i_mode) || f2fs_is_atomic_file(inode))
return false;
if (policy & (0x1 << F2FS_IPU_FORCE))