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    Subject[PATCH RESEND 2/2 block#for-linus] bio, fs: separate out bio_types.h and define READ/WRITE constants in terms of BIO_RW_* flags
    linux/fs.h hard coded READ/WRITE constants which should match BIO_RW_*
    flags. This is fragile and caused breakage during BIO_RW_* flag
    rearrangement. The hardcoding is to avoid include dependency hell.

    Create linux/bio_types.h which contatins definitions for bio data
    structures and flags and include it from bio.h and fs.h, and make fs.h
    define all READ/WRITE related constants in terms of BIO_RW_* flags.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Cc: Jens Axobe <axboe@kernel.dk>
    ---
    include/linux/bio.h | 153 +-----------------------------------------
    include/linux/bio_types.h | 164 ++++++++++++++++++++++++++++++++++++++++++++++
    include/linux/fs.h | 17 ++--
    3 files changed, 176 insertions(+), 158 deletions(-)

    Index: work/include/linux/bio.h
    ===================================================================
    --- work.orig/include/linux/bio.h
    +++ work/include/linux/bio.h
    @@ -9,7 +9,7 @@
    *
    * This program is distributed in the hope that it will be useful,
    * but WITHOUT ANY WARRANTY; without even the implied warranty of
    -
    + *
    * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    * GNU General Public License for more details.
    *
    @@ -28,6 +28,9 @@

    #include <asm/io.h>

    +/* struct bio, bio_vec and BIO_* flags are defined in bio_types.h */
    +#include <linux/bio_types.h>
    +
    #define BIO_DEBUG

    #ifdef BIO_DEBUG
    @@ -41,154 +44,6 @@
    #define BIO_MAX_SECTORS (BIO_MAX_SIZE >> 9)

    /*
    - * was unsigned short, but we might as well be ready for > 64kB I/O pages
    - */
    -struct bio_vec {
    - struct page *bv_page;
    - unsigned int bv_len;
    - unsigned int bv_offset;
    -};
    -
    -struct bio_set;
    -struct bio;
    -struct bio_integrity_payload;
    -typedef void (bio_end_io_t) (struct bio *, int);
    -typedef void (bio_destructor_t) (struct bio *);
    -
    -/*
    - * main unit of I/O for the block layer and lower layers (ie drivers and
    - * stacking drivers)
    - */
    -struct bio {
    - sector_t bi_sector; /* device address in 512 byte
    - sectors */
    - struct bio *bi_next; /* request queue link */
    - struct block_device *bi_bdev;
    - unsigned long bi_flags; /* status, command, etc */
    - unsigned long bi_rw; /* bottom bits READ/WRITE,
    - * top bits priority
    - */
    -
    - unsigned short bi_vcnt; /* how many bio_vec's */
    - unsigned short bi_idx; /* current index into bvl_vec */
    -
    - /* Number of segments in this BIO after
    - * physical address coalescing is performed.
    - */
    - unsigned int bi_phys_segments;
    -
    - unsigned int bi_size; /* residual I/O count */
    -
    - /*
    - * To keep track of the max segment size, we account for the
    - * sizes of the first and last mergeable segments in this bio.
    - */
    - unsigned int bi_seg_front_size;
    - unsigned int bi_seg_back_size;
    -
    - unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
    -
    - unsigned int bi_comp_cpu; /* completion CPU */
    -
    - atomic_t bi_cnt; /* pin count */
    -
    - struct bio_vec *bi_io_vec; /* the actual vec list */
    -
    - bio_end_io_t *bi_end_io;
    -
    - void *bi_private;
    -#if defined(CONFIG_BLK_DEV_INTEGRITY)
    - struct bio_integrity_payload *bi_integrity; /* data integrity */
    -#endif
    -
    - bio_destructor_t *bi_destructor; /* destructor */
    -
    - /*
    - * We can inline a number of vecs at the end of the bio, to avoid
    - * double allocations for a small number of bio_vecs. This member
    - * MUST obviously be kept at the very end of the bio.
    - */
    - struct bio_vec bi_inline_vecs[0];
    -};
    -
    -/*
    - * bio flags
    - */
    -#define BIO_UPTODATE 0 /* ok after I/O completion */
    -#define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */
    -#define BIO_EOF 2 /* out-out-bounds error */
    -#define BIO_SEG_VALID 3 /* bi_phys_segments valid */
    -#define BIO_CLONED 4 /* doesn't own data */
    -#define BIO_BOUNCED 5 /* bio is a bounce bio */
    -#define BIO_USER_MAPPED 6 /* contains user pages */
    -#define BIO_EOPNOTSUPP 7 /* not supported */
    -#define BIO_CPU_AFFINE 8 /* complete bio on same CPU as submitted */
    -#define BIO_NULL_MAPPED 9 /* contains invalid user pages */
    -#define BIO_FS_INTEGRITY 10 /* fs owns integrity data, not block layer */
    -#define BIO_QUIET 11 /* Make BIO Quiet */
    -#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
    -
    -/*
    - * top 4 bits of bio flags indicate the pool this bio came from
    - */
    -#define BIO_POOL_BITS (4)
    -#define BIO_POOL_NONE ((1UL << BIO_POOL_BITS) - 1)
    -#define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS)
    -#define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET)
    -#define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET)
    -
    -/*
    - * bio bi_rw flags
    - *
    - * bit 0 -- data direction
    - * If not set, bio is a read from device. If set, it's a write to device.
    - * bit 1 -- fail fast device errors
    - * bit 2 -- fail fast transport errors
    - * bit 3 -- fail fast driver errors
    - * bit 4 -- rw-ahead when set
    - * bit 5 -- barrier
    - * Insert a serialization point in the IO queue, forcing previously
    - * submitted IO to be completed before this one is issued.
    - * bit 6 -- synchronous I/O hint.
    - * bit 7 -- Unplug the device immediately after submitting this bio.
    - * bit 8 -- metadata request
    - * Used for tracing to differentiate metadata and data IO. May also
    - * get some preferential treatment in the IO scheduler
    - * bit 9 -- discard sectors
    - * Informs the lower level device that this range of sectors is no longer
    - * used by the file system and may thus be freed by the device. Used
    - * for flash based storage.
    - * Don't want driver retries for any fast fail whatever the reason.
    - * bit 10 -- Tell the IO scheduler not to wait for more requests after this
    - one has been submitted, even if it is a SYNC request.
    - */
    -enum bio_rw_flags {
    - BIO_RW,
    - BIO_RW_FAILFAST_DEV,
    - BIO_RW_FAILFAST_TRANSPORT,
    - BIO_RW_FAILFAST_DRIVER,
    - /* above flags must match REQ_* */
    - BIO_RW_AHEAD,
    - BIO_RW_BARRIER,
    - BIO_RW_SYNCIO,
    - BIO_RW_UNPLUG,
    - BIO_RW_META,
    - BIO_RW_DISCARD,
    - BIO_RW_NOIDLE,
    -};
    -
    -/*
    - * First four bits must match between bio->bi_rw and rq->cmd_flags, make
    - * that explicit here.
    - */
    -#define BIO_RW_RQ_MASK 0xf
    -
    -static inline bool bio_rw_flagged(struct bio *bio, enum bio_rw_flags flag)
    -{
    - return (bio->bi_rw & (1 << flag)) != 0;
    -}
    -
    -/*
    * upper 16 bits of bi_rw define the io priority of this bio
    */
    #define BIO_PRIO_SHIFT (8 * sizeof(unsigned long) - IOPRIO_BITS)
    Index: work/include/linux/bio_types.h
    ===================================================================
    --- /dev/null
    +++ work/include/linux/bio_types.h
    @@ -0,0 +1,164 @@
    +/*
    + * BIO data types and constants. Include linux/bio.h for usual cases.
    + * Directly include this file only to break include dependency loop.
    + */
    +#ifndef __LINUX_BIO_TYPES_H
    +#define __LINUX_BIO_TYPES_H
    +
    +#ifdef CONFIG_BLOCK
    +
    +#include <linux/types.h>
    +
    +struct bio_set;
    +struct bio;
    +struct bio_integrity_payload;
    +struct page;
    +struct block_device;
    +
    +/*
    + * was unsigned short, but we might as well be ready for > 64kB I/O pages
    + */
    +struct bio_vec {
    + struct page *bv_page;
    + unsigned int bv_len;
    + unsigned int bv_offset;
    +};
    +
    +typedef void (bio_end_io_t) (struct bio *, int);
    +typedef void (bio_destructor_t) (struct bio *);
    +
    +/*
    + * main unit of I/O for the block layer and lower layers (ie drivers and
    + * stacking drivers)
    + */
    +struct bio {
    + sector_t bi_sector; /* device address in 512 byte
    + sectors */
    + struct bio *bi_next; /* request queue link */
    + struct block_device *bi_bdev;
    + unsigned long bi_flags; /* status, command, etc */
    + unsigned long bi_rw; /* bottom bits READ/WRITE,
    + * top bits priority
    + */
    +
    + unsigned short bi_vcnt; /* how many bio_vec's */
    + unsigned short bi_idx; /* current index into bvl_vec */
    +
    + /* Number of segments in this BIO after
    + * physical address coalescing is performed.
    + */
    + unsigned int bi_phys_segments;
    +
    + unsigned int bi_size; /* residual I/O count */
    +
    + /*
    + * To keep track of the max segment size, we account for the
    + * sizes of the first and last mergeable segments in this bio.
    + */
    + unsigned int bi_seg_front_size;
    + unsigned int bi_seg_back_size;
    +
    + unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
    +
    + unsigned int bi_comp_cpu; /* completion CPU */
    +
    + atomic_t bi_cnt; /* pin count */
    +
    + struct bio_vec *bi_io_vec; /* the actual vec list */
    +
    + bio_end_io_t *bi_end_io;
    +
    + void *bi_private;
    +#if defined(CONFIG_BLK_DEV_INTEGRITY)
    + struct bio_integrity_payload *bi_integrity; /* data integrity */
    +#endif
    +
    + bio_destructor_t *bi_destructor; /* destructor */
    +
    + /*
    + * We can inline a number of vecs at the end of the bio, to avoid
    + * double allocations for a small number of bio_vecs. This member
    + * MUST obviously be kept at the very end of the bio.
    + */
    + struct bio_vec bi_inline_vecs[0];
    +};
    +
    +/*
    + * bio flags
    + */
    +#define BIO_UPTODATE 0 /* ok after I/O completion */
    +#define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */
    +#define BIO_EOF 2 /* out-out-bounds error */
    +#define BIO_SEG_VALID 3 /* bi_phys_segments valid */
    +#define BIO_CLONED 4 /* doesn't own data */
    +#define BIO_BOUNCED 5 /* bio is a bounce bio */
    +#define BIO_USER_MAPPED 6 /* contains user pages */
    +#define BIO_EOPNOTSUPP 7 /* not supported */
    +#define BIO_CPU_AFFINE 8 /* complete bio on same CPU as submitted */
    +#define BIO_NULL_MAPPED 9 /* contains invalid user pages */
    +#define BIO_FS_INTEGRITY 10 /* fs owns integrity data, not block layer */
    +#define BIO_QUIET 11 /* Make BIO Quiet */
    +#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
    +
    +/*
    + * top 4 bits of bio flags indicate the pool this bio came from
    + */
    +#define BIO_POOL_BITS (4)
    +#define BIO_POOL_NONE ((1UL << BIO_POOL_BITS) - 1)
    +#define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS)
    +#define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET)
    +#define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET)
    +
    +/*
    + * bio bi_rw flags
    + *
    + * bit 0 -- data direction
    + * If not set, bio is a read from device. If set, it's a write to device.
    + * bit 1 -- fail fast device errors
    + * bit 2 -- fail fast transport errors
    + * bit 3 -- fail fast driver errors
    + * bit 4 -- rw-ahead when set
    + * bit 5 -- barrier
    + * Insert a serialization point in the IO queue, forcing previously
    + * submitted IO to be completed before this one is issued.
    + * bit 6 -- synchronous I/O hint.
    + * bit 7 -- Unplug the device immediately after submitting this bio.
    + * bit 8 -- metadata request
    + * Used for tracing to differentiate metadata and data IO. May also
    + * get some preferential treatment in the IO scheduler
    + * bit 9 -- discard sectors
    + * Informs the lower level device that this range of sectors is no longer
    + * used by the file system and may thus be freed by the device. Used
    + * for flash based storage.
    + * Don't want driver retries for any fast fail whatever the reason.
    + * bit 10 -- Tell the IO scheduler not to wait for more requests after this
    + one has been submitted, even if it is a SYNC request.
    + */
    +enum bio_rw_flags {
    + BIO_RW,
    + BIO_RW_FAILFAST_DEV,
    + BIO_RW_FAILFAST_TRANSPORT,
    + BIO_RW_FAILFAST_DRIVER,
    + /* above flags must match REQ_* */
    + BIO_RW_AHEAD,
    + BIO_RW_BARRIER,
    + BIO_RW_SYNCIO,
    + BIO_RW_UNPLUG,
    + BIO_RW_META,
    + BIO_RW_DISCARD,
    + BIO_RW_NOIDLE,
    +};
    +
    +/*
    + * First four bits must match between bio->bi_rw and rq->cmd_flags, make
    + * that explicit here.
    + */
    +#define BIO_RW_RQ_MASK 0xf
    +
    +static inline bool bio_rw_flagged(struct bio *bio, enum bio_rw_flags flag)
    +{
    + return (bio->bi_rw & (1 << flag)) != 0;
    +}
    +
    +#endif /* CONFIG_BLOCK */
    +#endif /* __LINUX_BIO_TYPES_H */
    Index: work/include/linux/fs.h
    ===================================================================
    --- work.orig/include/linux/fs.h
    +++ work/include/linux/fs.h
    @@ -8,6 +8,7 @@

    #include <linux/limits.h>
    #include <linux/ioctl.h>
    +#include <linux/bio_types.h>

    /*
    * It's silly to have NR_OPEN bigger than NR_FILE, but you can change
    @@ -117,7 +118,7 @@ struct inodes_stat_t {
    * immediately wait on this read without caring about
    * unplugging.
    * READA Used for read-ahead operations. Lower priority, and the
    - * block layer could (in theory) choose to ignore this
    + * block layer could (in theory) choose to ignore this
    * request if it runs into resource problems.
    * WRITE A normal async write. Device will be plugged.
    * SWRITE Like WRITE, but a special case for ll_rw_block() that
    @@ -144,12 +145,12 @@ struct inodes_stat_t {
    * of this IO.
    *
    */
    -#define RW_MASK 1
    -#define RWA_MASK 2
    -#define READ 0
    -#define WRITE 1
    -#define READA 16 /* read-ahead - don't block if no resources */
    -#define SWRITE 17 /* for ll_rw_block() - wait for buffer lock */
    +#define RW_MASK (1 << BIO_RW)
    +#define RWA_MASK (1 << BIO_RW_AHEAD)
    +#define READ 0
    +#define WRITE RW_MASK
    +#define READA RWA_MASK
    +#define SWRITE (WRITE | READA)
    #define READ_SYNC (READ | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
    #define READ_META (READ | (1 << BIO_RW_META))
    #define WRITE_SYNC_PLUG (WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))
    @@ -2198,7 +2199,6 @@ static inline void insert_inode_hash(str
    extern void file_move(struct file *f, struct list_head *list);
    extern void file_kill(struct file *f);
    #ifdef CONFIG_BLOCK
    -struct bio;
    extern void submit_bio(int, struct bio *);
    extern int bdev_read_only(struct block_device *);
    #endif
    @@ -2265,7 +2265,6 @@ static inline int xip_truncate_page(stru
    #endif

    #ifdef CONFIG_BLOCK
    -struct bio;
    typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode,
    loff_t file_offset);
    void dio_end_io(struct bio *bio, int error);

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