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xfs: cap the length of deduplication requests

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Since deduplication potentially has to read in all the pages in both
files in order to compare the contents, cap the deduplication request
length at MAX_RW_COUNT/2 (roughly 1GB) so that we have /some/ upper bound
on the request length and can't just lock up the kernel forever.  Found
by running generic/304 after commit 1ddae54555b62 ("common/rc: add
missing 'local' keywords").

Reported-by: matorola@gmail.com
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
This commit is contained in:
Darrick J. Wong 2018-04-16 23:07:36 -07:00
parent 7b38460dc8
commit 021ba8e98f
1 changed files with 10 additions and 0 deletions
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10
fs/xfs/xfs_file.c
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@ -880,8 +880,18 @@ xfs_file_dedupe_range(
struct file *dst_file,
u64 dst_loff)
{
struct inode *srci = file_inode(src_file);
u64 max_dedupe;
int error;
/*
* Since we have to read all these pages in to compare them, cut
* it off at MAX_RW_COUNT/2 rounded down to the nearest block.
* That means we won't do more than MAX_RW_COUNT IO per request.
*/
max_dedupe = (MAX_RW_COUNT >> 1) & ~(i_blocksize(srci) - 1);
if (len > max_dedupe)
len = max_dedupe;
error = xfs_reflink_remap_range(src_file, loff, dst_file, dst_loff,
len, true);
if (error)