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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/uaccess.h>#include <asm/unistd.h>
/* * Performs necessary checks before doing a clone. * * Can adjust amount of bytes to clone via @req_count argument. * Returns appropriate error code that caller should return or * zero in case the clone should be allowed. */static int generic_remap_checks(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, loff_t *req_count, unsigned int remap_flags){ struct inode *inode_in = file_in->f_mapping->host; struct inode *inode_out = file_out->f_mapping->host; uint64_t count = *req_count; uint64_t bcount; loff_t size_in, size_out; loff_t bs = inode_out->i_sb->s_blocksize; int ret;
/* The start of both ranges must be aligned to an fs block. */ if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs)) return -EINVAL;
/* Ensure offsets don't wrap. */ if (pos_in + count < pos_in || pos_out + count < pos_out) return -EINVAL;
size_in = i_size_read(inode_in); size_out = i_size_read(inode_out);
/* Dedupe requires both ranges to be within EOF. */ if ((remap_flags & REMAP_FILE_DEDUP) && (pos_in >= size_in || pos_in + count > size_in || pos_out >= size_out || pos_out + count > size_out)) return -EINVAL;
/* Ensure the infile range is within the infile. */ if (pos_in >= size_in) return -EINVAL; count = min(count, size_in - (uint64_t)pos_in);
ret = generic_write_check_limits(file_out, pos_out, &count); if (ret) return ret;
/* * If the user wanted us to link to the infile's EOF, round up to the * next block boundary for this check. * * Otherwise, make sure the count is also block-aligned, having * already confirmed the starting offsets' block alignment. */ if (pos_in + count == size_in && (!(remap_flags & REMAP_FILE_DEDUP) || pos_out + count == size_out)) { bcount = ALIGN(size_in, bs) - pos_in; } else { if (!IS_ALIGNED(count, bs)) count = ALIGN_DOWN(count, bs); bcount = count; }
/* Don't allow overlapped cloning within the same file. */ if (inode_in == inode_out && pos_out + bcount > pos_in && pos_out < pos_in + bcount) return -EINVAL;
/* * 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;}
int remap_verify_area(struct file *file, loff_t pos, loff_t len, bool write){ int mask = write ? MAY_WRITE : MAY_READ; loff_t tmp; int ret;
if (unlikely(pos < 0 || len < 0)) return -EINVAL;
if (unlikely(check_add_overflow(pos, len, &tmp))) return -EINVAL;
ret = security_file_permission(file, mask); if (ret) return ret;
return fsnotify_file_area_perm(file, mask, &pos, len);}EXPORT_SYMBOL_GPL(remap_verify_area);
/* * Ensure that we don't remap a partial EOF block in the middle of something * else. Assume that the offsets have already been checked for block * alignment. * * For clone we only link a partial EOF block above or at the destination file's * EOF. For deduplication we accept a partial EOF block only if it ends at the * destination file's EOF (can not link it into the middle of a file). * * Shorten the request if possible. */static int generic_remap_check_len(struct inode *inode_in, struct inode *inode_out, loff_t pos_out, loff_t *len, unsigned int remap_flags){ u64 blkmask = i_blocksize(inode_in) - 1; loff_t new_len = *len;
if ((*len & blkmask) == 0) return 0;
if (pos_out + *len < i_size_read(inode_out)) new_len &= ~blkmask;
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;}
/* Read a page's worth of file data into the page cache. */static struct folio *vfs_dedupe_get_folio(struct file *file, loff_t pos){ return read_mapping_folio(file->f_mapping, pos >> PAGE_SHIFT, file);}
/* * Lock two folios, ensuring that we lock in offset order if the folios * are from the same file. */static void vfs_lock_two_folios(struct folio *folio1, struct folio *folio2){ /* Always lock in order of increasing index. */ if (folio1->index > folio2->index) swap(folio1, folio2);
folio_lock(folio1); if (folio1 != folio2) folio_lock(folio2);}
/* Unlock two folios, being careful not to unlock the same folio twice. */static void vfs_unlock_two_folios(struct folio *folio1, struct folio *folio2){ folio_unlock(folio1); if (folio1 != folio2) folio_unlock(folio2);}
/* * Compare extents of two files to see if they are the same. * Caller must have locked both inodes to prevent write races. */static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff, struct file *dest, loff_t dstoff, loff_t len, bool *is_same){ bool same = true; int error = -EINVAL;
while (len) { struct folio *src_folio, *dst_folio; void *src_addr, *dst_addr; loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff), PAGE_SIZE - offset_in_page(dstoff));
cmp_len = min(cmp_len, len); if (cmp_len <= 0) goto out_error;
src_folio = vfs_dedupe_get_folio(src, srcoff); if (IS_ERR(src_folio)) { error = PTR_ERR(src_folio); goto out_error; } dst_folio = vfs_dedupe_get_folio(dest, dstoff); if (IS_ERR(dst_folio)) { error = PTR_ERR(dst_folio); folio_put(src_folio); goto out_error; }
vfs_lock_two_folios(src_folio, dst_folio);
/* * Now that we've locked both folios, make sure they're still * mapped to the file data we're interested in. If not, * someone is invalidating pages on us and we lose. */ if (!folio_test_uptodate(src_folio) || !folio_test_uptodate(dst_folio) || src_folio->mapping != src->f_mapping || dst_folio->mapping != dest->f_mapping) { same = false; goto unlock; }
src_addr = kmap_local_folio(src_folio, offset_in_folio(src_folio, srcoff)); dst_addr = kmap_local_folio(dst_folio, offset_in_folio(dst_folio, dstoff));
flush_dcache_folio(src_folio); flush_dcache_folio(dst_folio);
if (memcmp(src_addr, dst_addr, cmp_len)) same = false;
kunmap_local(dst_addr); kunmap_local(src_addr);unlock: vfs_unlock_two_folios(src_folio, dst_folio); folio_put(dst_folio); folio_put(src_folio);
if (!same) break;
srcoff += cmp_len; dstoff += cmp_len; len -= cmp_len; }
*is_same = same; return 0;
out_error: return error;}
/* * Check that the two inodes are eligible for cloning, the ranges make * sense, and then flush all dirty data. Caller must ensure that the * inodes have been locked against any other modifications. * * If there's an error, then the usual negative error code is returned. * Otherwise returns 0 with *len set to the request length. */int__generic_remap_file_range_prep(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, loff_t *len, unsigned int remap_flags, const struct iomap_ops *dax_read_ops){ struct inode *inode_in = file_inode(file_in); struct inode *inode_out = file_inode(file_out); bool same_inode = (inode_in == inode_out); int ret;
/* Don't touch certain kinds of inodes */ if (IS_IMMUTABLE(inode_out)) return -EPERM;
if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out)) return -ETXTBSY;
/* Don't reflink dirs, pipes, sockets... */ if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode)) return -EISDIR; if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode)) return -EINVAL;
/* Zero length dedupe exits immediately; reflink goes to EOF. */ if (*len == 0) { loff_t isize = i_size_read(inode_in);
if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize) return 0; if (pos_in > isize) return -EINVAL; *len = isize - pos_in; if (*len == 0) return 0; }
/* Check that we don't violate system file offset limits. */ ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len, remap_flags); if (ret || *len == 0) return ret;
/* Wait for the completion of any pending IOs on both files */ inode_dio_wait(inode_in); if (!same_inode) inode_dio_wait(inode_out);
ret = filemap_write_and_wait_range(inode_in->i_mapping, pos_in, pos_in + *len - 1); if (ret) return ret;
ret = filemap_write_and_wait_range(inode_out->i_mapping, pos_out, pos_out + *len - 1); if (ret) return ret;
/* * Check that the extents are the same. */ if (remap_flags & REMAP_FILE_DEDUP) { bool is_same = false;
if (!IS_DAX(inode_in)) ret = vfs_dedupe_file_range_compare(file_in, pos_in, file_out, pos_out, *len, &is_same); else if (dax_read_ops) ret = dax_dedupe_file_range_compare(inode_in, pos_in, inode_out, pos_out, *len, &is_same, dax_read_ops); else return -EINVAL; if (ret) return ret; if (!is_same) return -EBADE; }
ret = generic_remap_check_len(inode_in, inode_out, pos_out, len, remap_flags); if (ret || *len == 0) return ret;
/* If can't alter the file contents, we're done. */ if (!(remap_flags & REMAP_FILE_DEDUP)) ret = file_modified(file_out);
return ret;}
int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, loff_t *len, unsigned int remap_flags){ return __generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out, len, remap_flags, NULL);}EXPORT_SYMBOL(generic_remap_file_range_prep);
loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, loff_t len, unsigned int remap_flags){ loff_t ret;
WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) return -EXDEV;
ret = generic_file_rw_checks(file_in, file_out); if (ret < 0) return ret;
if (!file_in->f_op->remap_file_range) return -EOPNOTSUPP;
ret = remap_verify_area(file_in, pos_in, len, false); if (ret) return ret;
ret = remap_verify_area(file_out, pos_out, len, true); if (ret) return ret;
file_start_write(file_out); ret = file_in->f_op->remap_file_range(file_in, pos_in, file_out, pos_out, len, remap_flags); file_end_write(file_out); if (ret < 0) return ret;
fsnotify_access(file_in); fsnotify_modify(file_out); return ret;}EXPORT_SYMBOL(vfs_clone_file_range);
/* Check whether we are allowed to dedupe the destination file */static bool may_dedupe_file(struct file *file){ struct mnt_idmap *idmap = file_mnt_idmap(file); struct inode *inode = file_inode(file);
if (capable(CAP_SYS_ADMIN)) return true; if (file->f_mode & FMODE_WRITE) return true; if (vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid())) return true; if (!inode_permission(idmap, inode, MAY_WRITE)) return true; return false;}
loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos, struct file *dst_file, loff_t dst_pos, loff_t len, unsigned int remap_flags){ loff_t ret;
WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_CAN_SHORTEN));
/* * This is redundant if called from vfs_dedupe_file_range(), but other * callers need it and it's not performance sesitive... */ ret = remap_verify_area(src_file, src_pos, len, false); if (ret) return ret;
ret = remap_verify_area(dst_file, dst_pos, len, true); if (ret) return ret;
/* * This needs to be called after remap_verify_area() because of * sb_start_write() and before may_dedupe_file() because the mount's * MAY_WRITE need to be checked with mnt_get_write_access_file() held. */ ret = mnt_want_write_file(dst_file); if (ret) return ret;
ret = -EPERM; if (!may_dedupe_file(dst_file)) goto out_drop_write;
ret = -EXDEV; if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb) goto out_drop_write;
ret = -EISDIR; if (S_ISDIR(file_inode(dst_file)->i_mode)) goto out_drop_write;
ret = -EINVAL; if (!dst_file->f_op->remap_file_range) goto out_drop_write;
if (len == 0) { ret = 0; goto out_drop_write; }
ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file, dst_pos, len, remap_flags | REMAP_FILE_DEDUP);out_drop_write: mnt_drop_write_file(dst_file);
return ret;}EXPORT_SYMBOL(vfs_dedupe_file_range_one);
int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same){ struct file_dedupe_range_info *info; struct inode *src = file_inode(file); u64 off; u64 len; int i; int ret; u16 count = same->dest_count; loff_t deduped;
if (!(file->f_mode & FMODE_READ)) return -EINVAL;
if (same->reserved1 || same->reserved2) return -EINVAL;
off = same->src_offset; len = same->src_length;
if (S_ISDIR(src->i_mode)) return -EISDIR;
if (!S_ISREG(src->i_mode)) return -EINVAL;
if (!file->f_op->remap_file_range) return -EOPNOTSUPP;
ret = remap_verify_area(file, off, len, false); if (ret < 0) return ret; ret = 0;
if (off + len > i_size_read(src)) return -EINVAL;
/* Arbitrary 1G limit on a single dedupe request, can be raised. */ len = min_t(u64, len, 1 << 30);
/* pre-format output fields to sane values */ for (i = 0; i < count; i++) { same->info[i].bytes_deduped = 0ULL; same->info[i].status = FILE_DEDUPE_RANGE_SAME; }
for (i = 0, info = same->info; i < count; i++, info++) { CLASS(fd, dst_fd)(info->dest_fd);
if (fd_empty(dst_fd)) { info->status = -EBADF; goto next_loop; }
if (info->reserved) { info->status = -EINVAL; goto next_loop; }
deduped = vfs_dedupe_file_range_one(file, off, fd_file(dst_fd), info->dest_offset, len, REMAP_FILE_CAN_SHORTEN); if (deduped == -EBADE) info->status = FILE_DEDUPE_RANGE_DIFFERS; else if (deduped < 0) info->status = deduped; else info->bytes_deduped = len;
next_loop: if (fatal_signal_pending(current)) break; } return ret;}EXPORT_SYMBOL(vfs_dedupe_file_range);