diff options
| -rw-r--r-- | fs/open.c | 1 | ||||
| -rw-r--r-- | include/linux/falloc.h | 3 | ||||
| -rw-r--r-- | include/uapi/linux/falloc.h | 17 |
3 files changed, 20 insertions, 1 deletions
diff --git a/fs/open.c b/fs/open.c index 7828234a7caa..b777e11e5522 100644 --- a/fs/open.c +++ b/fs/open.c @@ -281,6 +281,7 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) break; case FALLOC_FL_COLLAPSE_RANGE: case FALLOC_FL_INSERT_RANGE: + case FALLOC_FL_WRITE_ZEROES: if (mode & FALLOC_FL_KEEP_SIZE) return -EOPNOTSUPP; break; diff --git a/include/linux/falloc.h b/include/linux/falloc.h index 3f49f3df6af5..7c38c6b76b60 100644 --- a/include/linux/falloc.h +++ b/include/linux/falloc.h @@ -36,7 +36,8 @@ struct space_resv { FALLOC_FL_COLLAPSE_RANGE | \ FALLOC_FL_ZERO_RANGE | \ FALLOC_FL_INSERT_RANGE | \ - FALLOC_FL_UNSHARE_RANGE) + FALLOC_FL_UNSHARE_RANGE | \ + FALLOC_FL_WRITE_ZEROES) /* on ia32 l_start is on a 32-bit boundary */ #if defined(CONFIG_X86_64) diff --git a/include/uapi/linux/falloc.h b/include/uapi/linux/falloc.h index 5810371ed72b..1f9ca757d02d 100644 --- a/include/uapi/linux/falloc.h +++ b/include/uapi/linux/falloc.h @@ -78,4 +78,21 @@ */ #define FALLOC_FL_UNSHARE_RANGE 0x40 +/* + * FALLOC_FL_WRITE_ZEROES zeroes a specified file range in such a way that + * subsequent writes to that range do not require further changes to the file + * mapping metadata. This flag is beneficial for subsequent pure overwriting + * within this range, as it can save on block allocation and, consequently, + * significant metadata changes. Therefore, filesystems that always require + * out-of-place writes should not support this flag. + * + * Different filesystems may implement different limitations on the + * granularity of the zeroing operation. Most will preferably be accelerated + * by submitting write zeroes command if the backing storage supports, which + * may not physically write zeros to the media. + * + * This flag cannot be specified in conjunction with the FALLOC_FL_KEEP_SIZE. + */ +#define FALLOC_FL_WRITE_ZEROES 0x80 + #endif /* _UAPI_FALLOC_H_ */ |