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ceph: don't allow copy_file_range when stripe_count != 1
copy_file_range tries to use the OSD 'copy-from' operation, which simply performs a full object copy. Unfortunately, the implementation of this system call assumes that stripe_count is always set to 1 and doesn't take into account that the data may be striped across an object set. If the file layout has stripe_count different from 1, then the destination file data will be corrupted. For example: Consider a 8 MiB file with 4 MiB object size, stripe_count of 2 and stripe_size of 2 MiB; the first half of the file will be filled with 'A's and the second half will be filled with 'B's: 0 4M 8M Obj1 Obj2 +------+------+ +----+ +----+ file: | AAAA | BBBB | | AA | | AA | +------+------+ |----| |----| | BB | | BB | +----+ +----+ If we copy_file_range this file into a new file (which needs to have the same file layout!), then it will start by copying the object starting at file offset 0 (Obj1). And then it will copy the object starting at file offset 4M -- which is Obj1 again. Unfortunately, the solution for this is to not allow remote object copies to be performed when the file layout stripe_count is not 1 and simply fallback to the default (VFS) copy_file_range implementation. Cc: stable@vger.kernel.org Signed-off-by: Luis Henriques <lhenriques@suse.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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1 changed files with 10 additions and 2 deletions
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@ -1959,10 +1959,18 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
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if (ceph_test_mount_opt(src_fsc, NOCOPYFROM))
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return -EOPNOTSUPP;
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/*
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* Striped file layouts require that we copy partial objects, but the
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* OSD copy-from operation only supports full-object copies. Limit
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* this to non-striped file layouts for now.
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*/
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if ((src_ci->i_layout.stripe_unit != dst_ci->i_layout.stripe_unit) ||
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(src_ci->i_layout.stripe_count != dst_ci->i_layout.stripe_count) ||
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(src_ci->i_layout.object_size != dst_ci->i_layout.object_size))
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(src_ci->i_layout.stripe_count != 1) ||
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(dst_ci->i_layout.stripe_count != 1) ||
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(src_ci->i_layout.object_size != dst_ci->i_layout.object_size)) {
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dout("Invalid src/dst files layout\n");
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return -EOPNOTSUPP;
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}
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if (len < src_ci->i_layout.object_size)
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return -EOPNOTSUPP; /* no remote copy will be done */
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