On Tue, Apr 16, 2019 at 11:41:49AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>
> With dax we cannot deal with readpage() etc. So, we create a
> funciton callback to perform the file data comparison and pass
> it to generic_remap_file_range_prep() so it can use iomap-based
> functions.
>
> This may not be the best way to solve this. Suggestions welcome.
>
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
> ---
> fs/btrfs/ctree.h | 9 ++++++++
> fs/btrfs/dax.c | 7 +++++++
> fs/btrfs/ioctl.c | 11 ++++++++--
> fs/dax.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/ocfs2/file.c | 2 +-
> fs/read_write.c | 10 ++++-----
> fs/xfs/xfs_reflink.c | 2 +-
> include/linux/dax.h | 2 ++
> include/linux/fs.h | 7 ++++++-
> 9 files changed, 98 insertions(+), 10 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 2b7bdabb44f8..d3d044125619 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -3803,11 +3803,20 @@ int btree_readahead_hook(struct extent_buffer *eb, int err);
> ssize_t btrfs_file_dax_read(struct kiocb *iocb, struct iov_iter *to);
> ssize_t btrfs_file_dax_write(struct kiocb *iocb, struct iov_iter *from);
> vm_fault_t btrfs_dax_fault(struct vm_fault *vmf);
> +int btrfs_dax_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff, loff_t len,
> + bool *is_same);
> #else
> static inline ssize_t btrfs_file_dax_write(struct kiocb *iocb, struct iov_iter *from)
> {
> return 0;
> }
> +static inline int btrfs_dax_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff, loff_t len,
> + bool *is_same)
> +{
> + return 0;
> +}
> #endif /* CONFIG_FS_DAX */
>
> static inline int is_fstree(u64 rootid)
> diff --git a/fs/btrfs/dax.c b/fs/btrfs/dax.c
> index de957d681e16..a29628b403b3 100644
> --- a/fs/btrfs/dax.c
> +++ b/fs/btrfs/dax.c
> @@ -227,4 +227,11 @@ vm_fault_t btrfs_dax_fault(struct vm_fault *vmf)
>
> return ret;
> }
> +
> +int btrfs_dax_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff, loff_t len,
> + bool *is_same)
> +{
> + return dax_file_range_compare(src, srcoff, dest, destoff, len, is_same, &btrfs_iomap_ops);
> +}
> #endif /* CONFIG_FS_DAX */
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 0138119cd9a3..cd590105bd78 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -4000,8 +4000,15 @@ static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> if (ret < 0)
> goto out_unlock;
>
> - ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> - len, remap_flags);
> + if (IS_DAX(file_inode(file_in)) && IS_DAX(file_inode(file_out)))
> + ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
> + pos_out, len, remap_flags,
> + btrfs_dax_file_range_compare);
> + else
> + ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
> + pos_out, len, remap_flags,
> + vfs_dedupe_file_range_compare);
I wonder if you could simply have a compare_range_t variable that you
can set to either the vfs and btrfs_dax compare functions, and then only
have to maintain a single generic_remap_file_range_prep callsite?
> +
> if (ret < 0 || *len == 0)
> goto out_unlock;
>
> diff --git a/fs/dax.c b/fs/dax.c
> index d5100cbe8bd2..abbe4a79f219 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1759,3 +1759,61 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
> return dax_insert_pfn_mkwrite(vmf, pfn, order);
> }
> EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
> +
> +
> +int dax_file_range_compare(struct inode *src, loff_t srcoff, struct inode *dest,
> + loff_t destoff, loff_t len, bool *is_same, const struct iomap_ops *ops)
> +{
> + void *saddr, *daddr;
> + struct iomap s_iomap = {0};
> + struct iomap d_iomap = {0};
> + loff_t dstart, sstart;
> + bool same = true;
> + loff_t cmp_len, l;
> + int id, ret = 0;
> +
> + id = dax_read_lock();
> + while (len) {
> + ret = ops->iomap_begin(src, srcoff, len, 0, &s_iomap);
> + if (ret < 0) {
> + if (ops->iomap_end)
> + ops->iomap_end(src, srcoff, len, ret, 0, &s_iomap);
> + return ret;
> + }
> + cmp_len = len;
> + if (cmp_len > s_iomap.offset + s_iomap.length - srcoff)
> + cmp_len = s_iomap.offset + s_iomap.length - srcoff;
> +
> + ret = ops->iomap_begin(dest, destoff, cmp_len, 0, &d_iomap);
> + if (ret < 0) {
> + if (ops->iomap_end) {
> + ops->iomap_end(src, srcoff, len, ret, 0, &s_iomap);
> + ops->iomap_end(dest, destoff, len, ret, 0, &d_iomap);
> + }
> + return ret;
> + }
> + if (cmp_len > d_iomap.offset + d_iomap.length - destoff)
> + cmp_len = d_iomap.offset + d_iomap.length - destoff;
> +
> +
> + sstart = (get_start_sect(s_iomap.bdev) << 9) + s_iomap.addr + (srcoff - s_iomap.offset);
This kinda screams static inline helper function...
> + l = dax_direct_access(s_iomap.dax_dev, PHYS_PFN(sstart), PHYS_PFN(cmp_len), &saddr, NULL);
> + dstart = (get_start_sect(d_iomap.bdev) << 9) + d_iomap.addr + (destoff - d_iomap.offset);
...especially since it happens again here...
> + l = dax_direct_access(d_iomap.dax_dev, PHYS_PFN(dstart), PHYS_PFN(cmp_len), &daddr, NULL);
...and these lines are too long.
> + same = !memcmp(saddr, daddr, cmp_len);
> + if (!same)
> + break;
> + len -= cmp_len;
> + srcoff += cmp_len;
> + destoff += cmp_len;
> +
> + if (ops->iomap_end) {
> + ret = ops->iomap_end(src, srcoff, len, 0, 0, &s_iomap);
> + ret = ops->iomap_end(dest, destoff, len, 0, 0, &d_iomap);
> + }
> + }
> + dax_read_unlock(id);
> + *is_same = same;
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(dax_file_range_compare);
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index d640c5f8a85d..9d470306cfc3 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2558,7 +2558,7 @@ static loff_t ocfs2_remap_file_range(struct file *file_in, loff_t pos_in,
> goto out_unlock;
>
> ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> - &len, remap_flags);
> + &len, remap_flags, vfs_dedupe_file_range_compare);
> if (ret < 0 || len == 0)
> goto out_unlock;
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 61b43ad7608e..ecc67740d0ff 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1778,7 +1778,7 @@ static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
> * Compare extents of two files to see if they are the same.
> * Caller must have locked both inodes to prevent write races.
> */
> -static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> +int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> struct inode *dest, loff_t destoff,
> loff_t len, bool *is_same)
> {
> @@ -1845,6 +1845,7 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> out_error:
> return error;
> }
> +EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
Not EXPORT_SYMBOL_GPL? :D
> /*
> * Check that the two inodes are eligible for cloning, the ranges make
> @@ -1856,7 +1857,7 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> */
> int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> - loff_t *len, unsigned int remap_flags)
> + loff_t *len, unsigned int remap_flags, compare_range_t compare)
> {
> struct inode *inode_in = file_inode(file_in);
> struct inode *inode_out = file_inode(file_out);
> @@ -1915,9 +1916,8 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> */
> if (remap_flags & REMAP_FILE_DEDUP) {
> bool is_same = false;
> -
> - ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> - inode_out, pos_out, *len, &is_same);
> + ret = compare(inode_in, pos_in,
> + inode_out, pos_out, *len, &is_same);
> if (ret)
> return ret;
> if (!is_same)
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 680ae7662a78..68e4257cebb0 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1350,7 +1350,7 @@ xfs_reflink_remap_prep(
> goto out_unlock;
>
> ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> - len, remap_flags);
> + len, remap_flags, vfs_dedupe_file_range_compare);
> if (ret < 0 || *len == 0)
> goto out_unlock;
>
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 0dd316a74a29..a11bc7b1f526 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -157,6 +157,8 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
> int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
> int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
> pgoff_t index);
> +int dax_file_range_compare(struct inode *src, loff_t srcoff, struct inode *dest,
> + loff_t destoff, loff_t len, bool *is_same, const struct iomap_ops *ops);
>
> #ifdef CONFIG_FS_DAX
> int __dax_zero_page_range(struct block_device *bdev,
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index dd28e7679089..b1aa2fc105ae 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1883,10 +1883,15 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
> unsigned long, loff_t *, rwf_t);
> extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
> loff_t, size_t, unsigned int);
> +extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff,
> + loff_t len, bool *is_same);
> +typedef int (compare_range_t)(struct inode *src, loff_t srcpos, struct inode *dest,
> + loff_t destpos, loff_t len, bool *is_same);
Might want to call this vfs_compare_range_t to make it clear that this
belongs to the generic vfs namespace.
--D
> extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> loff_t *count,
> - unsigned int remap_flags);
> + unsigned int remap_flags, compare_range_t cmp);
> extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> loff_t len, unsigned int remap_flags);
> --
> 2.16.4
>
