From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx> Add new flag(FALLOC_FL_COLLAPSE_RANGE) for fallocate. updated detailed semantics in comments. Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx> Signed-off-by: Ashish Sangwan <a.sangwan@xxxxxxxxxxx> --- fs/open.c | 24 +++++++++++++++++++++--- include/uapi/linux/falloc.h | 21 +++++++++++++++++++++ 2 files changed, 42 insertions(+), 3 deletions(-) diff --git a/fs/open.c b/fs/open.c index 4b3e1ed..4a923a5 100644 --- a/fs/open.c +++ b/fs/open.c @@ -231,7 +231,8 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) return -EINVAL; /* Return error if mode is not supported */ - if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) + if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | + FALLOC_FL_COLLAPSE_RANGE)) return -EOPNOTSUPP; /* Punch hole must have keep size set */ @@ -239,11 +240,20 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) !(mode & FALLOC_FL_KEEP_SIZE)) return -EOPNOTSUPP; + /* Collapse range should only be used exclusively. */ + if ((mode & FALLOC_FL_COLLAPSE_RANGE) && + (mode & ~FALLOC_FL_COLLAPSE_RANGE)) + return -EINVAL; + if (!(file->f_mode & FMODE_WRITE)) return -EBADF; - /* It's not possible punch hole on append only file */ - if (mode & FALLOC_FL_PUNCH_HOLE && IS_APPEND(inode)) + /* + * It's not possible to punch hole or perform collapse range + * on append only file + */ + if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE) + && IS_APPEND(inode)) return -EPERM; if (IS_IMMUTABLE(inode)) @@ -271,6 +281,14 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) return -EFBIG; + /* + * There is no need to overlap collapse range with EOF, in which case + * it is effectively a truncate operation + */ + if ((mode & FALLOC_FL_COLLAPSE_RANGE) && + (offset + len >= i_size_read(inode))) + return -EINVAL; + if (!file->f_op->fallocate) return -EOPNOTSUPP; diff --git a/include/uapi/linux/falloc.h b/include/uapi/linux/falloc.h index 990c4cc..5b214cc 100644 --- a/include/uapi/linux/falloc.h +++ b/include/uapi/linux/falloc.h @@ -5,5 +5,26 @@ #define FALLOC_FL_PUNCH_HOLE 0x02 /* de-allocates range */ #define FALLOC_FL_NO_HIDE_STALE 0x04 /* reserved codepoint */ +/* + * FALLOC_FL_COLLAPSE_RANGE is used to remove a range of a file + * without leaving a hole in the file. The contents of the file beyond + * the range being removed is appended to the start offset of the range + * being removed (i.e. the hole that was punched is "collapsed"), + * resulting in a file layout that looks like the range that was + * removed never existed. As such collapsing a range of a file changes + * the size of the file, reducing it by the same length of the range + * that has been removed by the operation. + * + * Different filesystems may implement different limitations on the + * granularity of the operation. Most will limit operations to + * filesystem block size boundaries, but this boundary may be larger or + * smaller depending on the filesystem and/or the configuration of the + * filesystem or file. + * + * Attempting to collapse a range that crosses the end of the file is + * considered an illegal operation - just use ftruncate(2) if you need + * to collapse a range that crosses EOF. + */ +#define FALLOC_FL_COLLAPSE_RANGE 0x08 #endif /* _UAPI_FALLOC_H_ */ -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
