From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: [PATCH 17/26] 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: Mon, 15 Oct 2018 20:19:54 -0700 Message-ID: <153965999426.3607.3221368918901209000.stgit@magnolia> In-Reply-To: <153965939489.1256.7400115244528045860.stgit@magnolia> References: <153965939489.1256.7400115244528045860.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.). We also enable CAN_SHORTEN for fideduperange to maintain existing userspace-visible behavior where xfs/btrfs shorten the dedupe range to avoid stale post-eof data exposure. Signed-off-by: Darrick J. Wong Reviewed-by: Amir Goldstein --- fs/read_write.c | 28 ++++++++++++++++++++-------- include/linux/fs.h | 7 +++++-- mm/filemap.c | 16 ++++++++++++---- 3 files changed, 37 insertions(+), 14 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index f6ab5beb935a..ee9314b7bfc3 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), + REMAP_FILE_CAN_SHORTEN); if (cloned > 0) { ret = cloned; goto done; @@ -1721,6 +1722,8 @@ static int remap_verify_area(struct file *file, loff_t pos, loff_t len, * can't meaningfully compare post-EOF contents. * * For clone we only link a partial EOF block above the destination file's EOF. + * + * Shorten the request if possible. */ static int generic_remap_check_len(struct inode *inode_in, struct inode *inode_out, @@ -1729,16 +1732,24 @@ static int generic_remap_check_len(struct inode *inode_in, unsigned int remap_flags) { u64 blkmask = i_blocksize(inode_in) - 1; + loff_t new_len = *len; if ((*len & blkmask) == 0) return 0; - if (remap_flags & REMAP_FILE_DEDUP) - *len &= ~blkmask; - else if (pos_out + *len < i_size_read(inode_out)) - return -EINVAL; + if ((remap_flags & REMAP_FILE_DEDUP) || + pos_out + *len < i_size_read(inode_out)) + new_len &= ~blkmask; - return 0; + if (new_len == *len) + return 0; + + if (remap_flags & REMAP_FILE_CAN_SHORTEN) { + *len = new_len; + return 0; + } + + return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL; } /* Update inode timestamps and remove security privileges when remapping. */ @@ -2023,7 +2034,8 @@ loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos, { loff_t ret; - WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP)); + WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP | + REMAP_FILE_CAN_SHORTEN)); ret = mnt_want_write_file(dst_file); if (ret) @@ -2124,7 +2136,7 @@ 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); + REMAP_FILE_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 c0ae85a7bd9d..594fe4ba0b15 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1726,14 +1726,17 @@ struct block_device_operations; * If it is called with len == 0 that means "remap to end of source file". * * REMAP_FILE_DEDUP: only remap if contents identical (i.e. deduplicate) + * REMAP_FILE_CAN_SHORTEN: caller can handle a shortened request */ #define REMAP_FILE_DEDUP (1 << 0) +#define REMAP_FILE_CAN_SHORTEN (1 << 1) /* All valid REMAP_FILE flags */ -#define REMAP_FILE_VALID_FLAGS (REMAP_FILE_DEDUP) +#define REMAP_FILE_VALID_FLAGS (REMAP_FILE_DEDUP | \ + REMAP_FILE_CAN_SHORTEN) /* REMAP_FILE flags taken care of by the vfs. */ -#define REMAP_FILE_ADVISORY (0) +#define REMAP_FILE_ADVISORY (REMAP_FILE_CAN_SHORTEN) struct iov_iter; diff --git a/mm/filemap.c b/mm/filemap.c index 1e93269efafe..898eb358f7d2 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 & REMAP_FILE_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 & REMAP_FILE_CAN_SHORTEN)) return -EINVAL; + *req_count = count; return 0; }