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vfs: check file ranges before cloning files

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Move the file range checks from vfs_clone_file_prep into a separate
generic_remap_checks function so that all the checks are collected in a
central location.  This forms the basis for adding more checks from
generic_write_checks that will make cloning's input checking more
consistent with write input checking.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Darrick J. Wong
2018-10-30 10:40:31 +11:00
committed by Dave Chinner
parent 5b49f64db2
commit 1383a7ed67
5 changed files with 90 additions and 47 deletions
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69
mm/filemap.c
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@@ -2974,6 +2974,75 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
}
EXPORT_SYMBOL(generic_write_checks);
/*
* Performs necessary checks before doing a clone.
*
* Can adjust amount of bytes to clone.
* Returns appropriate error code that caller should return or
* zero in case the clone should be allowed.
*/
int generic_remap_checks(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
uint64_t *req_count, bool is_dedupe)
{
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;
/* 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 (is_dedupe &&
(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);
/*
* 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) {
bcount = ALIGN(size_in, bs) - pos_in;
} else {
if (!IS_ALIGNED(count, bs))
return -EINVAL;
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;
/* For now we don't support changing the length. */
if (*req_count != count)
return -EINVAL;
return 0;
}
int pagecache_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)