From ae259a9c8593f98aa60d045df978a5482a67c53f Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 21 Jun 2016 09:23:11 +1000 Subject: fs: introduce iomap infrastructure Add infrastructure for multipage buffered writes. This is implemented using an main iterator that applies an actor function to a range that can be written. This infrastucture is used to implement a buffered write helper, one to zero file ranges and one to implement the ->page_mkwrite VM operations. All of them borrow a fair amount of code from fs/buffers. for now by using an internal version of __block_write_begin that gets passed an iomap and builds the corresponding buffer head. The file system is gets a set of paired ->iomap_begin and ->iomap_end calls which allow it to map/reserve a range and get a notification once the write code is finished with it. Based on earlier code from Dave Chinner. Signed-off-by: Christoph Hellwig Reviewed-by: Bob Peterson Signed-off-by: Dave Chinner --- include/linux/iomap.h | 56 ++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 51 insertions(+), 5 deletions(-) (limited to 'include/linux/iomap.h') diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 1b22197bcf01..d2f469ae899a 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -3,19 +3,65 @@ #include -/* types of block ranges for multipage write mappings. */ +struct inode; +struct iov_iter; +struct kiocb; +struct vm_area_struct; +struct vm_fault; + +/* + * Types of block ranges for iomap mappings: + */ #define IOMAP_HOLE 0x01 /* no blocks allocated, need allocation */ #define IOMAP_DELALLOC 0x02 /* delayed allocation blocks */ #define IOMAP_MAPPED 0x03 /* blocks allocated @blkno */ #define IOMAP_UNWRITTEN 0x04 /* blocks allocated @blkno in unwritten state */ +/* + * Magic value for blkno: + */ #define IOMAP_NULL_BLOCK -1LL /* blkno is not valid */ struct iomap { - sector_t blkno; /* first sector of mapping */ - loff_t offset; /* file offset of mapping, bytes */ - u64 length; /* length of mapping, bytes */ - int type; /* type of mapping */ + sector_t blkno; /* 1st sector of mapping, 512b units */ + loff_t offset; /* file offset of mapping, bytes */ + u64 length; /* length of mapping, bytes */ + int type; /* type of mapping */ + struct block_device *bdev; /* block device for I/O */ +}; + +/* + * Flags for iomap_begin / iomap_end. No flag implies a read. + */ +#define IOMAP_WRITE (1 << 0) +#define IOMAP_ZERO (1 << 1) + +struct iomap_ops { + /* + * Return the existing mapping at pos, or reserve space starting at + * pos for up to length, as long as we can do it as a single mapping. + * The actual length is returned in iomap->length. + */ + int (*iomap_begin)(struct inode *inode, loff_t pos, loff_t length, + unsigned flags, struct iomap *iomap); + + /* + * Commit and/or unreserve space previous allocated using iomap_begin. + * Written indicates the length of the successful write operation which + * needs to be commited, while the rest needs to be unreserved. + * Written might be zero if no data was written. + */ + int (*iomap_end)(struct inode *inode, loff_t pos, loff_t length, + ssize_t written, unsigned flags, struct iomap *iomap); }; +ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from, + struct iomap_ops *ops); +int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, + bool *did_zero, struct iomap_ops *ops); +int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, + struct iomap_ops *ops); +int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, + struct iomap_ops *ops); + #endif /* LINUX_IOMAP_H */ -- cgit v1.2.3-59-g8ed1b