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02e83f46eb
I would like to move all the generic helpers for the vfs remap range functionality (aka clonerange and dedupe) into a separate file so that they won't be scattered across the vfs and the mm subsystems. The eventual goal is to be able to deselect remap_range.c if none of the filesystems need that code, but the tricky part here is picking a stable(ish) part of the merge window to rearrange code. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/sched/xacct.h>
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#include <linux/fcntl.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/fsnotify.h>
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#include <linux/security.h>
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#include <linux/export.h>
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#include <linux/syscalls.h>
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#include <linux/pagemap.h>
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#include <linux/splice.h>
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#include <linux/compat.h>
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#include <linux/mount.h>
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#include <linux/fs.h>
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#include "internal.h"
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#include <linux/uaccess.h>
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#include <asm/unistd.h>
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/*
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* Performs necessary checks before doing a clone.
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*
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* Can adjust amount of bytes to clone via @req_count argument.
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* Returns appropriate error code that caller should return or
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* zero in case the clone should be allowed.
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*/
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int generic_remap_checks(struct file *file_in, loff_t pos_in,
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struct file *file_out, loff_t pos_out,
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loff_t *req_count, unsigned int remap_flags)
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{
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struct inode *inode_in = file_in->f_mapping->host;
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struct inode *inode_out = file_out->f_mapping->host;
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uint64_t count = *req_count;
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uint64_t bcount;
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loff_t size_in, size_out;
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loff_t bs = inode_out->i_sb->s_blocksize;
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int ret;
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/* The start of both ranges must be aligned to an fs block. */
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if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
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return -EINVAL;
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/* Ensure offsets don't wrap. */
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if (pos_in + count < pos_in || pos_out + count < pos_out)
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return -EINVAL;
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size_in = i_size_read(inode_in);
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size_out = i_size_read(inode_out);
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/* Dedupe requires both ranges to be within EOF. */
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if ((remap_flags & REMAP_FILE_DEDUP) &&
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(pos_in >= size_in || pos_in + count > size_in ||
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pos_out >= size_out || pos_out + count > size_out))
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return -EINVAL;
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/* Ensure the infile range is within the infile. */
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if (pos_in >= size_in)
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return -EINVAL;
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count = min(count, size_in - (uint64_t)pos_in);
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ret = generic_write_check_limits(file_out, pos_out, &count);
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if (ret)
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return ret;
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/*
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* If the user wanted us to link to the infile's EOF, round up to the
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* next block boundary for this check.
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*
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* Otherwise, make sure the count is also block-aligned, having
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* already confirmed the starting offsets' block alignment.
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*/
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if (pos_in + count == size_in) {
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bcount = ALIGN(size_in, bs) - pos_in;
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} else {
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if (!IS_ALIGNED(count, bs))
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count = ALIGN_DOWN(count, bs);
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bcount = count;
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}
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/* Don't allow overlapped cloning within the same file. */
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if (inode_in == inode_out &&
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pos_out + bcount > pos_in &&
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pos_out < pos_in + bcount)
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return -EINVAL;
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/*
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* We shortened the request but the caller can't deal with that, so
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* bounce the request back to userspace.
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*/
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if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
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return -EINVAL;
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*req_count = count;
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return 0;
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}
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