On Fri, Sep 25, 2015 at 04:48:14PM -0400, Anna Schumaker wrote: > The NFS server will need some kind offallback for filesystems that don't
"some kind of fallback" > have any kind of copy acceleration, and it should be generally useful to > have an in-kernel copy to avoid lots of switches between kernel and user > space. > > I make this configurable by adding two new flags. Users who only want a > reflink can pass COPY_FR_REFLINK, and users who want a full data copy can > pass COPY_FR_COPY. The default (flags=0) means to first attempt a > reflink, but use the pagecache if that fails. "The COPY_FR_DEDUPE flag makes a reflink, but only if the contents of both file ranges are identical." > I moved the rw_verify_area() calls into the fallback code since some > filesystems can handle reflinking a large range. > > Signed-off-by: Anna Schumaker <[email protected]> > --- > v3: > - Check that both filesystems have the same filesystem type > - Add COPY_FR_DEDUPE flag for Darrick > - Check that at most one flag is set at a time > --- > fs/read_write.c | 61 > +++++++++++++++++++++++++++++++---------------- > include/linux/copy.h | 6 +++++ > include/uapi/linux/Kbuild | 1 + > include/uapi/linux/copy.h | 8 +++++++ > 4 files changed, 56 insertions(+), 20 deletions(-) > create mode 100644 include/linux/copy.h > create mode 100644 include/uapi/linux/copy.h > > diff --git a/fs/read_write.c b/fs/read_write.c > index ee9fa37..a0fd9dc 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -7,6 +7,7 @@ > #include <linux/slab.h> > #include <linux/stat.h> > #include <linux/fcntl.h> > +#include <linux/copy.h> > #include <linux/file.h> > #include <linux/uio.h> > #include <linux/fsnotify.h> > @@ -1329,6 +1330,29 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, > in_fd, > } > #endif > > +static ssize_t vfs_copy_file_pagecache(struct file *file_in, loff_t pos_in, > + struct file *file_out, loff_t pos_out, > + size_t len) > +{ > + ssize_t ret; > + > + ret = rw_verify_area(READ, file_in, &pos_in, len); > + if (ret >= 0) { > + len = ret; > + ret = rw_verify_area(WRITE, file_out, &pos_out, len); > + if (ret >= 0) > + len = ret; > + } > + if (ret < 0) > + return ret; > + > + file_start_write(file_out); > + ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out, len, 0); > + file_end_write(file_out); > + > + return ret; > +} > + > /* > * copy_file_range() differs from regular file read and write in that it > * specifically allows return partial success. When it does so is up to > @@ -1338,34 +1362,26 @@ ssize_t vfs_copy_file_range(struct file *file_in, > loff_t pos_in, > struct file *file_out, loff_t pos_out, > size_t len, unsigned int flags) > { > - struct inode *inode_in; > - struct inode *inode_out; > ssize_t ret; > > - if (flags) > + /* Flags should only be used exclusively. */ > + if ((flags & COPY_FR_COPY) && (flags & ~COPY_FR_COPY)) > return -EINVAL; > + if ((flags & COPY_FR_REFLINK) && (flags & ~COPY_FR_REFLINK)) > + return -EINVAL; > + if (flags & COPY_FR_DEDUPE) > + return -EOPNOTSUPP; Since dedupe can't be combined with copy or reflink either, we might as well say: if ((flags & COPY_FR_DEDUPE) && (flags & ~COPY_FR_DEDUPE)) return -EINVAL; and let the per-fs copy_file_range()s dispatch appropriately. Otherwise, you can add: Reviewed-by: Darrick J. Wong <[email protected]> --D > > - /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */ > - ret = rw_verify_area(READ, file_in, &pos_in, len); > - if (ret >= 0) > - ret = rw_verify_area(WRITE, file_out, &pos_out, len); > - if (ret < 0) > - return ret; > + /* Default behavior is to try both. */ > + if (flags == 0) > + flags = COPY_FR_COPY | COPY_FR_REFLINK; > > if (!(file_in->f_mode & FMODE_READ) || > !(file_out->f_mode & FMODE_WRITE) || > (file_out->f_flags & O_APPEND) || > - !file_out->f_op || !file_out->f_op->copy_file_range) > + !file_out->f_op) > return -EBADF; > > - inode_in = file_inode(file_in); > - inode_out = file_inode(file_out); > - > - /* make sure offsets don't wrap and the input is inside i_size */ > - if (pos_in + len < pos_in || pos_out + len < pos_out || > - pos_in + len > i_size_read(inode_in)) > - return -EINVAL; > - > if (len == 0) > return 0; > > @@ -1373,8 +1389,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, > loff_t pos_in, > if (ret) > return ret; > > - ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, > pos_out, > - len, flags); > + ret = -EOPNOTSUPP; > + if (file_out->f_op->copy_file_range && (file_in->f_op == > file_out->f_op)) > + ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, > + pos_out, len, flags); > + if ((ret < 0) && (flags & COPY_FR_COPY)) > + ret = vfs_copy_file_pagecache(file_in, pos_in, file_out, > + pos_out, len); > if (ret > 0) { > fsnotify_access(file_in); > add_rchar(current, ret); > diff --git a/include/linux/copy.h b/include/linux/copy.h > new file mode 100644 > index 0000000..fd54543 > --- /dev/null > +++ b/include/linux/copy.h > @@ -0,0 +1,6 @@ > +#ifndef _LINUX_COPY_H > +#define _LINUX_COPY_H > + > +#include <uapi/linux/copy.h> > + > +#endif /* _LINUX_COPY_H */ > diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild > index f7b2db4..faafd67 100644 > --- a/include/uapi/linux/Kbuild > +++ b/include/uapi/linux/Kbuild > @@ -90,6 +90,7 @@ header-y += coda_psdev.h > header-y += coff.h > header-y += connector.h > header-y += const.h > +header-y += copy.h > header-y += cramfs_fs.h > header-y += cuda.h > header-y += cyclades.h > diff --git a/include/uapi/linux/copy.h b/include/uapi/linux/copy.h > new file mode 100644 > index 0000000..6225838 > --- /dev/null > +++ b/include/uapi/linux/copy.h > @@ -0,0 +1,8 @@ > +#ifndef _UAPI_LINUX_COPY_H > +#define _UAPI_LINUX_COPY_H > + > +#define COPY_FR_COPY (1 << 0) /* Only do a pagecache copy. */ > +#define COPY_FR_REFLINK (1 << 1) /* Only make a reflink. > */ > +#define COPY_FR_DEDUPE (1 << 2) /* Deduplicate file data. > */ > + > +#endif /* _UAPI_LINUX_COPY_H */ > -- > 2.5.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-api" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
