f2fs: introduce F2FS_IOC_START_ATOMIC_REPLACE

introduce a new ioctl to replace the whole content of a file atomically,
which means it induces truncate and content update at the same time.
We can start it with F2FS_IOC_START_ATOMIC_REPLACE and complete it with
F2FS_IOC_COMMIT_ATOMIC_WRITE. Or abort it with
F2FS_IOC_ABORT_ATOMIC_WRITE.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 9b47ded..560fa80 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3466,6 +3466,9 @@ static int prepare_atomic_write_begin(struct f2fs_sb_info *sbi,
        else if (*blk_addr != NULL_ADDR)
                return 0;
 
+       if (is_inode_flag_set(inode, FI_ATOMIC_REPLACE))
+               goto reserve_block;
+
        /* Look for the block in the original inode */
        err = __find_data_block(inode, index, &ori_blk_addr);
        if (err)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 6a8cbf5..b89b5d7 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -769,6 +769,7 @@ enum {
        FI_ALIGNED_WRITE,       /* enable aligned write */
        FI_COW_FILE,            /* indicate COW file */
        FI_ATOMIC_COMMITTED,    /* indicate atomic commit completed except disk sync */
+       FI_ATOMIC_REPLACE,      /* indicate atomic replace */
        FI_MAX,                 /* max flag, never be used */
 };
 

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 28f586e..ab0a0d3 100644 (file)
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2034,7 +2034,7 @@ static int f2fs_ioc_getversion(struct file *filp, unsigned long arg)
        return put_user(inode->i_generation, (int __user *)arg);
 }
 
-static int f2fs_ioc_start_atomic_write(struct file *filp)
+static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 {
        struct inode *inode = file_inode(filp);
        struct user_namespace *mnt_userns = file_mnt_user_ns(filp);
@@ -2103,15 +2103,22 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
 
        f2fs_write_inode(inode, NULL);
 
-       isize = i_size_read(inode);
-       fi->original_i_size = isize;
-       f2fs_i_size_write(fi->cow_inode, isize);
-
        stat_inc_atomic_inode(inode);
 
        set_inode_flag(inode, FI_ATOMIC_FILE);
        set_inode_flag(fi->cow_inode, FI_COW_FILE);
        clear_inode_flag(fi->cow_inode, FI_INLINE_DATA);
+
+       isize = i_size_read(inode);
+       fi->original_i_size = isize;
+       if (truncate) {
+               set_inode_flag(inode, FI_ATOMIC_REPLACE);
+               truncate_inode_pages_final(inode->i_mapping);
+               f2fs_i_size_write(inode, 0);
+               isize = 0;
+       }
+       f2fs_i_size_write(fi->cow_inode, isize);
+
        f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
 
        f2fs_update_time(sbi, REQ_TIME);
@@ -4139,7 +4146,9 @@ static long __f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
        case FS_IOC_GETVERSION:
                return f2fs_ioc_getversion(filp, arg);
        case F2FS_IOC_START_ATOMIC_WRITE:
-               return f2fs_ioc_start_atomic_write(filp);
+               return f2fs_ioc_start_atomic_write(filp, false);
+       case F2FS_IOC_START_ATOMIC_REPLACE:
+               return f2fs_ioc_start_atomic_write(filp, true);
        case F2FS_IOC_COMMIT_ATOMIC_WRITE:
                return f2fs_ioc_commit_atomic_write(filp);
        case F2FS_IOC_ABORT_ATOMIC_WRITE:

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8aa8123..5ac026a 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -197,6 +197,7 @@ void f2fs_abort_atomic_write(struct inode *inode, bool clean)
        fi->cow_inode = NULL;
        release_atomic_write_cnt(inode);
        clear_inode_flag(inode, FI_ATOMIC_COMMITTED);
+       clear_inode_flag(inode, FI_ATOMIC_REPLACE);
        clear_inode_flag(inode, FI_ATOMIC_FILE);
        stat_dec_atomic_inode(inode);
 
@@ -261,14 +262,24 @@ static void __complete_revoke_list(struct inode *inode, struct list_head *head,
                                        bool revoke)
 {
        struct revoke_entry *cur, *tmp;
+       pgoff_t start_index = 0;
+       bool truncate = is_inode_flag_set(inode, FI_ATOMIC_REPLACE);
 
        list_for_each_entry_safe(cur, tmp, head, list) {
-               if (revoke)
+               if (revoke) {
                        __replace_atomic_write_block(inode, cur->index,
                                                cur->old_addr, NULL, true);
+               } else if (truncate) {
+                       f2fs_truncate_hole(inode, start_index, cur->index);
+                       start_index = cur->index + 1;
+               }
+
                list_del(&cur->list);
                kmem_cache_free(revoke_entry_slab, cur);
        }
+
+       if (!revoke && truncate)
+               f2fs_do_truncate_blocks(inode, start_index * PAGE_SIZE, false);
 }
 
 static int __f2fs_commit_atomic_write(struct inode *inode)

diff --git a/include/uapi/linux/f2fs.h b/include/uapi/linux/f2fs.h
index 3121d12..955d440 100644 (file)
--- a/include/uapi/linux/f2fs.h
+++ b/include/uapi/linux/f2fs.h
@@ -42,6 +42,7 @@
                                                struct f2fs_comp_option)
 #define F2FS_IOC_DECOMPRESS_FILE       _IO(F2FS_IOCTL_MAGIC, 23)
 #define F2FS_IOC_COMPRESS_FILE         _IO(F2FS_IOCTL_MAGIC, 24)
+#define F2FS_IOC_START_ATOMIC_REPLACE  _IO(F2FS_IOCTL_MAGIC, 25)
 
 /*
  * should be same as XFS_IOC_GOINGDOWN.