| Message ID | 379c680ae1e6309e679ff83bc6cb55e1cf97d7f9.1415220890.git.milosz@adfin.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 5 Nov 2014, Milosz Tanski wrote: > generic_file_read_iter() supports a new flag RWF_NONBLOCK which says that we > only want to read the data if it's already in the page cache. > > Additionally, there are a few filesystems that we have to specifically > bail early if RWF_NONBLOCK because the op would block. Christoph Hellwig > contributed this code. > > Signed-off-by: Milosz Tanski <milosz@adfin.com> > Reviewed-by: Christoph Hellwig <hch@lst.de> > Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Ceph bits Acked-by: Sage Weil <sage@redhat.com> > --- > fs/ceph/file.c | 2 ++ > fs/cifs/file.c | 6 ++++++ > fs/nfs/file.c | 5 ++++- > fs/ocfs2/file.c | 6 ++++++ > fs/pipe.c | 3 ++- > fs/read_write.c | 38 +++++++++++++++++++++++++------------- > fs/xfs/xfs_file.c | 4 ++++ > include/linux/fs.h | 3 +++ > mm/filemap.c | 18 ++++++++++++++++++ > mm/shmem.c | 4 ++++ > 10 files changed, 74 insertions(+), 15 deletions(-) > > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > index d7e0da8..b798b5c 100644 > --- a/fs/ceph/file.c > +++ b/fs/ceph/file.c > @@ -822,6 +822,8 @@ again: > if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 || > (iocb->ki_filp->f_flags & O_DIRECT) || > (fi->flags & CEPH_F_SYNC)) { > + if (iocb->ki_rwflags & O_NONBLOCK) > + return -EAGAIN; > > dout("aio_sync_read %p %llx.%llx %llu~%u got cap refs on %s\n", > inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index 3e4d00a..c485afa 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -3005,6 +3005,9 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) > struct cifs_readdata *rdata, *tmp; > struct list_head rdata_list; > > + if (iocb->ki_rwflags & RWF_NONBLOCK) > + return -EAGAIN; > + > len = iov_iter_count(to); > if (!len) > return 0; > @@ -3123,6 +3126,9 @@ cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to) > ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) > return generic_file_read_iter(iocb, to); > > + if (iocb->ki_rwflags & RWF_NONBLOCK) > + return -EAGAIN; > + > /* > * We need to hold the sem to be sure nobody modifies lock list > * with a brlock that prevents reading. > diff --git a/fs/nfs/file.c b/fs/nfs/file.c > index 2ab6f00..aa9046f 100644 > --- a/fs/nfs/file.c > +++ b/fs/nfs/file.c > @@ -171,8 +171,11 @@ nfs_file_read(struct kiocb *iocb, struct iov_iter *to) > struct inode *inode = file_inode(iocb->ki_filp); > ssize_t result; > > - if (iocb->ki_filp->f_flags & O_DIRECT) > + if (iocb->ki_filp->f_flags & O_DIRECT) { > + if (iocb->ki_rwflags & O_NONBLOCK) > + return -EAGAIN; > return nfs_file_direct_read(iocb, to, iocb->ki_pos); > + } > > dprintk("NFS: read(%pD2, %zu@%lu)\n", > iocb->ki_filp, > diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c > index 324dc93..bb66ca4 100644 > --- a/fs/ocfs2/file.c > +++ b/fs/ocfs2/file.c > @@ -2472,6 +2472,12 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb, > filp->f_path.dentry->d_name.name, > to->nr_segs); /* GRRRRR */ > > + /* > + * No non-blocking reads for ocfs2 for now. Might be doable with > + * non-blocking cluster lock helpers. > + */ > + if (iocb->ki_rwflags & RWF_NONBLOCK) > + return -EAGAIN; > > if (!inode) { > ret = -EINVAL; > diff --git a/fs/pipe.c b/fs/pipe.c > index 21981e5..212bf68 100644 > --- a/fs/pipe.c > +++ b/fs/pipe.c > @@ -302,7 +302,8 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) > */ > if (ret) > break; > - if (filp->f_flags & O_NONBLOCK) { > + if ((filp->f_flags & O_NONBLOCK) || > + (iocb->ki_rwflags & RWF_NONBLOCK)) { > ret = -EAGAIN; > break; > } > diff --git a/fs/read_write.c b/fs/read_write.c > index 907735c..cba7d4c 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -835,14 +835,19 @@ static ssize_t do_readv_writev(int type, struct file *file, > file_start_write(file); > } > > - if (iter_fn) > + if (iter_fn) { > ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len, > pos, iter_fn, flags); > - else if (fnv) > - ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, > - pos, fnv); > - else > - ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); > + } else { > + if (type == READ && (flags & RWF_NONBLOCK)) > + return -EAGAIN; > + > + if (fnv) > + ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, > + pos, fnv); > + else > + ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); > + } > > if (type != READ) > file_end_write(file); > @@ -866,8 +871,10 @@ ssize_t vfs_readv(struct file *file, const struct iovec __user *vec, > return -EBADF; > if (!(file->f_mode & FMODE_CAN_READ)) > return -EINVAL; > - if (flags & ~0) > + if (flags & ~RWF_NONBLOCK) > return -EINVAL; > + if ((file->f_flags & O_DIRECT) && (flags & RWF_NONBLOCK)) > + return -EAGAIN; > > return do_readv_writev(READ, file, vec, vlen, pos, flags); > } > @@ -1069,14 +1076,19 @@ static ssize_t compat_do_readv_writev(int type, struct file *file, > file_start_write(file); > } > > - if (iter_fn) > + if (iter_fn) { > ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len, > pos, iter_fn, flags); > - else if (fnv) > - ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, > - pos, fnv); > - else > - ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); > + } else { > + if (type == READ && (flags & RWF_NONBLOCK)) > + return -EAGAIN; > + > + if (fnv) > + ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, > + pos, fnv); > + else > + ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); > + } > > if (type != READ) > file_end_write(file); > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index eb596b4..b1f6334 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -246,6 +246,10 @@ xfs_file_read_iter( > > XFS_STATS_INC(xs_read_calls); > > + /* XXX: need a non-blocking iolock helper, shouldn't be too hard */ > + if (iocb->ki_rwflags & RWF_NONBLOCK) > + return -EAGAIN; > + > if (unlikely(file->f_flags & O_DIRECT)) > ioflags |= XFS_IO_ISDIRECT; > if (file->f_mode & FMODE_NOCMTIME) > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 9ed5711..eaebd99 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1459,6 +1459,9 @@ struct block_device_operations; > #define HAVE_COMPAT_IOCTL 1 > #define HAVE_UNLOCKED_IOCTL 1 > > +/* These flags are used for the readv/writev syscalls with flags. */ > +#define RWF_NONBLOCK 0x00000001 > + > struct iov_iter; > > struct file_operations { > diff --git a/mm/filemap.c b/mm/filemap.c > index 530c263..09d3af3 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1494,6 +1494,8 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos, > find_page: > page = find_get_page(mapping, index); > if (!page) { > + if (flags & RWF_NONBLOCK) > + goto would_block; > page_cache_sync_readahead(mapping, > ra, filp, > index, last_index - index); > @@ -1585,6 +1587,11 @@ page_ok: > continue; > > page_not_up_to_date: > + if (flags & RWF_NONBLOCK) { > + page_cache_release(page); > + goto would_block; > + } > + > /* Get exclusive access to the page ... */ > error = lock_page_killable(page); > if (unlikely(error)) > @@ -1604,6 +1611,12 @@ page_not_up_to_date_locked: > goto page_ok; > } > > + if (flags & RWF_NONBLOCK) { > + unlock_page(page); > + page_cache_release(page); > + goto would_block; > + } > + > readpage: > /* > * A previous I/O error may have been due to temporary > @@ -1674,6 +1687,8 @@ no_cached_page: > goto readpage; > } > > +would_block: > + error = -EAGAIN; > out: > ra->prev_pos = prev_index; > ra->prev_pos <<= PAGE_CACHE_SHIFT; > @@ -1707,6 +1722,9 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) > size_t count = iov_iter_count(iter); > loff_t size; > > + if (iocb->ki_rwflags & RWF_NONBLOCK) > + return -EAGAIN; > + > if (!count) > goto out; /* skip atime */ > size = i_size_read(inode); > diff --git a/mm/shmem.c b/mm/shmem.c > index cd6fc75..5c30f04 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1531,6 +1531,10 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) > ssize_t retval = 0; > loff_t *ppos = &iocb->ki_pos; > > + /* XXX: should be easily supportable */ > + if (iocb->ki_rwflags & RWF_NONBLOCK) > + return -EAGAIN; > + > /* > * Might this read be for a stacking filesystem? Then when reading > * holes of a sparse file, we actually need to allocate those pages, > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ceph/file.c b/fs/ceph/file.c index d7e0da8..b798b5c 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -822,6 +822,8 @@ again: if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 || (iocb->ki_filp->f_flags & O_DIRECT) || (fi->flags & CEPH_F_SYNC)) { + if (iocb->ki_rwflags & O_NONBLOCK) + return -EAGAIN; dout("aio_sync_read %p %llx.%llx %llu~%u got cap refs on %s\n", inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 3e4d00a..c485afa 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -3005,6 +3005,9 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) struct cifs_readdata *rdata, *tmp; struct list_head rdata_list; + if (iocb->ki_rwflags & RWF_NONBLOCK) + return -EAGAIN; + len = iov_iter_count(to); if (!len) return 0; @@ -3123,6 +3126,9 @@ cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to) ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) return generic_file_read_iter(iocb, to); + if (iocb->ki_rwflags & RWF_NONBLOCK) + return -EAGAIN; + /* * We need to hold the sem to be sure nobody modifies lock list * with a brlock that prevents reading. diff --git a/fs/nfs/file.c b/fs/nfs/file.c index 2ab6f00..aa9046f 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -171,8 +171,11 @@ nfs_file_read(struct kiocb *iocb, struct iov_iter *to) struct inode *inode = file_inode(iocb->ki_filp); ssize_t result; - if (iocb->ki_filp->f_flags & O_DIRECT) + if (iocb->ki_filp->f_flags & O_DIRECT) { + if (iocb->ki_rwflags & O_NONBLOCK) + return -EAGAIN; return nfs_file_direct_read(iocb, to, iocb->ki_pos); + } dprintk("NFS: read(%pD2, %zu@%lu)\n", iocb->ki_filp, diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c index 324dc93..bb66ca4 100644 --- a/fs/ocfs2/file.c +++ b/fs/ocfs2/file.c @@ -2472,6 +2472,12 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb, filp->f_path.dentry->d_name.name, to->nr_segs); /* GRRRRR */ + /* + * No non-blocking reads for ocfs2 for now. Might be doable with + * non-blocking cluster lock helpers. + */ + if (iocb->ki_rwflags & RWF_NONBLOCK) + return -EAGAIN; if (!inode) { ret = -EINVAL; diff --git a/fs/pipe.c b/fs/pipe.c index 21981e5..212bf68 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -302,7 +302,8 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) */ if (ret) break; - if (filp->f_flags & O_NONBLOCK) { + if ((filp->f_flags & O_NONBLOCK) || + (iocb->ki_rwflags & RWF_NONBLOCK)) { ret = -EAGAIN; break; } diff --git a/fs/read_write.c b/fs/read_write.c index 907735c..cba7d4c 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -835,14 +835,19 @@ static ssize_t do_readv_writev(int type, struct file *file, file_start_write(file); } - if (iter_fn) + if (iter_fn) { ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len, pos, iter_fn, flags); - else if (fnv) - ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, - pos, fnv); - else - ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); + } else { + if (type == READ && (flags & RWF_NONBLOCK)) + return -EAGAIN; + + if (fnv) + ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, + pos, fnv); + else + ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); + } if (type != READ) file_end_write(file); @@ -866,8 +871,10 @@ ssize_t vfs_readv(struct file *file, const struct iovec __user *vec, return -EBADF; if (!(file->f_mode & FMODE_CAN_READ)) return -EINVAL; - if (flags & ~0) + if (flags & ~RWF_NONBLOCK) return -EINVAL; + if ((file->f_flags & O_DIRECT) && (flags & RWF_NONBLOCK)) + return -EAGAIN; return do_readv_writev(READ, file, vec, vlen, pos, flags); } @@ -1069,14 +1076,19 @@ static ssize_t compat_do_readv_writev(int type, struct file *file, file_start_write(file); } - if (iter_fn) + if (iter_fn) { ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len, pos, iter_fn, flags); - else if (fnv) - ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, - pos, fnv); - else - ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); + } else { + if (type == READ && (flags & RWF_NONBLOCK)) + return -EAGAIN; + + if (fnv) + ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, + pos, fnv); + else + ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); + } if (type != READ) file_end_write(file); diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index eb596b4..b1f6334 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -246,6 +246,10 @@ xfs_file_read_iter( XFS_STATS_INC(xs_read_calls); + /* XXX: need a non-blocking iolock helper, shouldn't be too hard */ + if (iocb->ki_rwflags & RWF_NONBLOCK) + return -EAGAIN; + if (unlikely(file->f_flags & O_DIRECT)) ioflags |= XFS_IO_ISDIRECT; if (file->f_mode & FMODE_NOCMTIME) diff --git a/include/linux/fs.h b/include/linux/fs.h index 9ed5711..eaebd99 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1459,6 +1459,9 @@ struct block_device_operations; #define HAVE_COMPAT_IOCTL 1 #define HAVE_UNLOCKED_IOCTL 1 +/* These flags are used for the readv/writev syscalls with flags. */ +#define RWF_NONBLOCK 0x00000001 + struct iov_iter; struct file_operations { diff --git a/mm/filemap.c b/mm/filemap.c index 530c263..09d3af3 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1494,6 +1494,8 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos, find_page: page = find_get_page(mapping, index); if (!page) { + if (flags & RWF_NONBLOCK) + goto would_block; page_cache_sync_readahead(mapping, ra, filp, index, last_index - index); @@ -1585,6 +1587,11 @@ page_ok: continue; page_not_up_to_date: + if (flags & RWF_NONBLOCK) { + page_cache_release(page); + goto would_block; + } + /* Get exclusive access to the page ... */ error = lock_page_killable(page); if (unlikely(error)) @@ -1604,6 +1611,12 @@ page_not_up_to_date_locked: goto page_ok; } + if (flags & RWF_NONBLOCK) { + unlock_page(page); + page_cache_release(page); + goto would_block; + } + readpage: /* * A previous I/O error may have been due to temporary @@ -1674,6 +1687,8 @@ no_cached_page: goto readpage; } +would_block: + error = -EAGAIN; out: ra->prev_pos = prev_index; ra->prev_pos <<= PAGE_CACHE_SHIFT; @@ -1707,6 +1722,9 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) size_t count = iov_iter_count(iter); loff_t size; + if (iocb->ki_rwflags & RWF_NONBLOCK) + return -EAGAIN; + if (!count) goto out; /* skip atime */ size = i_size_read(inode); diff --git a/mm/shmem.c b/mm/shmem.c index cd6fc75..5c30f04 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1531,6 +1531,10 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) ssize_t retval = 0; loff_t *ppos = &iocb->ki_pos; + /* XXX: should be easily supportable */ + if (iocb->ki_rwflags & RWF_NONBLOCK) + return -EAGAIN; + /* * Might this read be for a stacking filesystem? Then when reading * holes of a sparse file, we actually need to allocate those pages,