From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: [PATCH 17/25] vfs: enable remap callers that can handle short operations From: "Darrick J. Wong" To: david@fromorbit.com, darrick.wong@oracle.com Cc: sandeen@redhat.com, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, Amir Goldstein , linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, ocfs2-devel@oss.oracle.com Date: Wed, 10 Oct 2018 21:14:26 -0700 Message-ID: <153923126628.5546.3484461137192547927.stgit@magnolia> In-Reply-To: <153923113649.5546.9840926895953408273.stgit@magnolia> References: <153923113649.5546.9840926895953408273.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: From: Darrick J. Wong Plumb in a remap flag that enables the filesystem remap handler to shorten remapping requests for callers that can handle it. Now copy_file_range can report partial success (in case we run up against alignment problems, resource limits, etc.). Signed-off-by: Darrick J. Wong Reviewed-by: Amir Goldstein --- fs/read_write.c | 15 +++++++++------ include/linux/fs.h | 7 +++++-- mm/filemap.c | 16 ++++++++++++---- 3 files changed, 26 insertions(+), 12 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index 6ec908f9a69b..3713893b7e38 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1593,7 +1593,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, cloned = file_in->f_op->remap_file_range(file_in, pos_in, file_out, pos_out, - min_t(loff_t, MAX_RW_COUNT, len), 0); + min_t(loff_t, MAX_RW_COUNT, len), + RFR_CAN_SHORTEN); if (cloned > 0) { ret = cloned; goto done; @@ -1804,16 +1805,18 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in, * If the user is attempting to remap a partial EOF block and * it's inside the destination EOF then reject it. * - * We don't support shortening requests, so we can only reject - * them. + * If possible, shorten the request instead of rejecting it. */ if (is_dedupe) ret = -EBADE; else if (pos_out + *len < i_size_read(inode_out)) ret = -EINVAL; - if (ret) - return ret; + if (ret) { + if (!(remap_flags & RFR_CAN_SHORTEN)) + return ret; + *len &= ~blkmask; + } } return 1; @@ -2112,7 +2115,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same) deduped = vfs_dedupe_file_range_one(file, off, dst_file, info->dest_offset, len, - 0); + RFR_CAN_SHORTEN); if (deduped == -EBADE) info->status = FILE_DEDUPE_RANGE_DIFFERS; else if (deduped < 0) diff --git a/include/linux/fs.h b/include/linux/fs.h index b9c314f9d5a4..57cb56bbc30a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1726,14 +1726,17 @@ struct block_device_operations; * * RFR_SAME_DATA: only remap if contents identical (i.e. deduplicate) * RFR_TO_SRC_EOF: remap to the end of the source file + * RFR_CAN_SHORTEN: caller can handle a shortened request */ #define RFR_SAME_DATA (1 << 0) #define RFR_TO_SRC_EOF (1 << 1) +#define RFR_CAN_SHORTEN (1 << 2) -#define RFR_VALID_FLAGS (RFR_SAME_DATA | RFR_TO_SRC_EOF) +#define RFR_VALID_FLAGS (RFR_SAME_DATA | RFR_TO_SRC_EOF | \ + RFR_CAN_SHORTEN) /* Implemented by the VFS, so these are advisory. */ -#define RFR_VFS_FLAGS (RFR_TO_SRC_EOF) +#define RFR_VFS_FLAGS (RFR_TO_SRC_EOF | RFR_CAN_SHORTEN) /* * Filesystem remapping implementations should call this helper on their diff --git a/mm/filemap.c b/mm/filemap.c index 369cfd164e90..bccbd3621238 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3051,8 +3051,12 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in, if (pos_in + count == size_in) { bcount = ALIGN(size_in, bs) - pos_in; } else { - if (!IS_ALIGNED(count, bs)) - return -EINVAL; + if (!IS_ALIGNED(count, bs)) { + if (remap_flags & RFR_CAN_SHORTEN) + count = ALIGN_DOWN(count, bs); + else + return -EINVAL; + } bcount = count; } @@ -3063,10 +3067,14 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in, pos_out < pos_in + bcount) return -EINVAL; - /* For now we don't support changing the length. */ - if (*req_count != count) + /* + * We shortened the request but the caller can't deal with that, so + * bounce the request back to userspace. + */ + if (*req_count != count && !(remap_flags & RFR_CAN_SHORTEN)) return -EINVAL; + *req_count = count; return 0; }