diff options
| -rw-r--r-- | Documentation/filesystems/f2fs.txt | 25 | ||||
| -rw-r--r-- | fs/f2fs/file.c | 7 |
2 files changed, 31 insertions, 1 deletions
diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt index bebd1be3ba49..496fa28b2492 100644 --- a/Documentation/filesystems/f2fs.txt +++ b/Documentation/filesystems/f2fs.txt @@ -804,3 +804,28 @@ WRITE_LIFE_NOT_SET WARM_DATA WRITE_LIFE_NOT_SET WRITE_LIFE_NONE " WRITE_LIFE_NONE WRITE_LIFE_MEDIUM " WRITE_LIFE_MEDIUM WRITE_LIFE_LONG " WRITE_LIFE_LONG + +Fallocate(2) Policy +------------------- + +The default policy follows the below posix rule. + +Allocating disk space + The default operation (i.e., mode is zero) of fallocate() allocates + the disk space within the range specified by offset and len. The + file size (as reported by stat(2)) will be changed if offset+len is + greater than the file size. Any subregion within the range specified + by offset and len that did not contain data before the call will be + initialized to zero. This default behavior closely resembles the + behavior of the posix_fallocate(3) library function, and is intended + as a method of optimally implementing that function. + +However, once F2FS receives ioctl(fd, F2FS_IOC_SET_PIN_FILE) in prior to +fallocate(fd, DEFAULT_MODE), it allocates on-disk blocks addressess having +zero or random data, which is useful to the below scenario where: + 1. create(fd) + 2. ioctl(fd, F2FS_IOC_SET_PIN_FILE) + 3. fallocate(fd, 0, 0, size) + 4. address = fibmap(fd, offset) + 5. open(blkdev) + 6. write(blkdev, address) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index c67ff5057472..b164f48e0f31 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1528,7 +1528,12 @@ static int expand_inode_data(struct inode *inode, loff_t offset, if (off_end) map.m_len++; - err = f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_AIO); + if (f2fs_is_pinned_file(inode)) + map.m_seg_type = CURSEG_COLD_DATA; + + err = f2fs_map_blocks(inode, &map, 1, (f2fs_is_pinned_file(inode) ? + F2FS_GET_BLOCK_PRE_DIO : + F2FS_GET_BLOCK_PRE_AIO)); if (err) { pgoff_t last_off; |