From 046ba64285a4389ae5e9a7dfa253c6bff3d7c341 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Tue, 6 Jan 2015 16:10:37 -0800 Subject: target: Drop arbitrary maximum I/O size limit This patch drops the arbitrary maximum I/O size limit in sbc_parse_cdb(), which currently for fabric_max_sectors is hardcoded to 8192 (4 MB for 512 byte sector devices), and for hw_max_sectors is a backend driver dependent value. This limit is problematic because Linux initiators have only recently started to honor block limits MAXIMUM TRANSFER LENGTH, and other non-Linux based initiators (eg: MSFT Fibre Channel) can also generate I/Os larger than 4 MB in size. Currently when this happens, the following message will appear on the target resulting in I/Os being returned with non recoverable status: SCSI OP 28h with too big sectors 16384 exceeds fabric_max_sectors: 8192 Instead, drop both [fabric,hw]_max_sector checks in sbc_parse_cdb(), and convert the existing hw_max_sectors into a purely informational attribute used to represent the granuality that backend driver and/or subsystem code is splitting I/Os upon. Also, update FILEIO with an explicit FD_MAX_BYTES check in fd_execute_rw() to deal with the one special iovec limitiation case. v2 changes: - Drop hw_max_sectors check in sbc_parse_cdb() Reported-by: Lance Gropper Reported-by: Stefan Priebe Cc: Christoph Hellwig Cc: Martin K. Petersen Cc: Roland Dreier Cc: stable@vger.kernel.org # 3.4 Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_file.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'drivers/target/target_core_file.c') diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c index c2aea099ea4a..b09021135c3b 100644 --- a/drivers/target/target_core_file.c +++ b/drivers/target/target_core_file.c @@ -621,7 +621,16 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, struct fd_prot fd_prot; sense_reason_t rc; int ret = 0; - + /* + * We are currently limited by the number of iovecs (2048) per + * single vfs_[writev,readv] call. + */ + if (cmd->data_length > FD_MAX_BYTES) { + pr_err("FILEIO: Not able to process I/O of %u bytes due to" + "FD_MAX_BYTES: %u iovec count limitiation\n", + cmd->data_length, FD_MAX_BYTES); + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; + } /* * Call vectorized fileio functions to map struct scatterlist * physical memory addresses to struct iovec virtual memory. -- cgit v1.2.3