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/file.c b/fs/f2fs/file.c
index 735e9a2..3708b80 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -862,6 +862,41 @@
return ret;
}
+static int f2fs_ioc_start_atomic_write(struct file *filp)
+{
+ struct inode *inode = file_inode(filp);
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+
+ if (!inode_owner_or_capable(inode))
+ return -EACCES;
+
+ f2fs_balance_fs(sbi);
+
+ set_inode_flag(F2FS_I(inode), FI_ATOMIC_FILE);
+
+ return f2fs_convert_inline_data(inode, MAX_INLINE_DATA + 1, NULL);
+}
+
+static int f2fs_ioc_commit_atomic_write(struct file *filp)
+{
+ struct inode *inode = file_inode(filp);
+ int ret;
+
+ if (!inode_owner_or_capable(inode))
+ return -EACCES;
+
+ ret = mnt_want_write_file(filp);
+ if (ret)
+ return ret;
+
+ if (f2fs_is_atomic_file(inode))
+ commit_inmem_pages(inode, false);
+
+ ret = f2fs_sync_file(filp, 0, LONG_MAX, 0);
+ mnt_drop_write_file(filp);
+ return ret;
+}
+
static int f2fs_ioc_fitrim(struct file *filp, unsigned long arg)
{
struct inode *inode = file_inode(filp);
@@ -899,6 +934,10 @@
return f2fs_ioc_getflags(filp, arg);
case F2FS_IOC_SETFLAGS:
return f2fs_ioc_setflags(filp, arg);
+ case F2FS_IOC_START_ATOMIC_WRITE:
+ return f2fs_ioc_start_atomic_write(filp);
+ case F2FS_IOC_COMMIT_ATOMIC_WRITE:
+ return f2fs_ioc_commit_atomic_write(filp);
case FITRIM:
return f2fs_ioc_fitrim(filp, arg);
default: