Commit b32f4c7ed85c5cee2a21a55c9f59ebc9d57a2463
1 parent
f25590f39d
Exists in
smarc-l5.0.0_1.0.0-ga
and in
5 other branches
target/file: Re-enable optional fd_buffered_io=1 operation
This patch re-adds the ability to optionally run in buffered FILEIO mode (eg: w/o O_DSYNC) for device backends in order to once again use the Linux buffered cache as a write-back storage mechanism. This logic was originally dropped with mainline v3.5-rc commit: commit a4dff3043c231d57f982af635c9d2192ee40e5ae Author: Nicholas Bellinger <nab@linux-iscsi.org> Date: Wed May 30 16:25:41 2012 -0700 target/file: Use O_DSYNC by default for FILEIO backends This difference with this patch is that fd_create_virtdevice() now forces the explicit setting of emulate_write_cache=1 when buffered FILEIO operation has been enabled. (v2: Switch to FDBD_HAS_BUFFERED_IO_WCE + add more detailed comment as requested by hch) Reported-by: Ferry <iscsitmp@bananateam.nl> Cc: Christoph Hellwig <hch@lst.de> Cc: <stable@vger.kernel.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Showing 2 changed files with 39 additions and 3 deletions Side-by-side Diff
drivers/target/target_core_file.c
| ... | ... | @@ -125,6 +125,19 @@ |
| 125 | 125 | * of pure timestamp updates. |
| 126 | 126 | */ |
| 127 | 127 | flags = O_RDWR | O_CREAT | O_LARGEFILE | O_DSYNC; |
| 128 | + /* | |
| 129 | + * Optionally allow fd_buffered_io=1 to be enabled for people | |
| 130 | + * who want use the fs buffer cache as an WriteCache mechanism. | |
| 131 | + * | |
| 132 | + * This means that in event of a hard failure, there is a risk | |
| 133 | + * of silent data-loss if the SCSI client has *not* performed a | |
| 134 | + * forced unit access (FUA) write, or issued SYNCHRONIZE_CACHE | |
| 135 | + * to write-out the entire device cache. | |
| 136 | + */ | |
| 137 | + if (fd_dev->fbd_flags & FDBD_HAS_BUFFERED_IO_WCE) { | |
| 138 | + pr_debug("FILEIO: Disabling O_DSYNC, using buffered FILEIO\n"); | |
| 139 | + flags &= ~O_DSYNC; | |
| 140 | + } | |
| 128 | 141 | |
| 129 | 142 | file = filp_open(fd_dev->fd_dev_name, flags, 0600); |
| 130 | 143 | if (IS_ERR(file)) { |
| ... | ... | @@ -188,6 +201,12 @@ |
| 188 | 201 | if (!dev) |
| 189 | 202 | goto fail; |
| 190 | 203 | |
| 204 | + if (fd_dev->fbd_flags & FDBD_HAS_BUFFERED_IO_WCE) { | |
| 205 | + pr_debug("FILEIO: Forcing setting of emulate_write_cache=1" | |
| 206 | + " with FDBD_HAS_BUFFERED_IO_WCE\n"); | |
| 207 | + dev->se_sub_dev->se_dev_attrib.emulate_write_cache = 1; | |
| 208 | + } | |
| 209 | + | |
| 191 | 210 | fd_dev->fd_dev_id = fd_host->fd_host_dev_id_count++; |
| 192 | 211 | fd_dev->fd_queue_depth = dev->queue_depth; |
| 193 | 212 | |
| ... | ... | @@ -407,6 +426,7 @@ |
| 407 | 426 | static match_table_t tokens = { |
| 408 | 427 | {Opt_fd_dev_name, "fd_dev_name=%s"}, |
| 409 | 428 | {Opt_fd_dev_size, "fd_dev_size=%s"}, |
| 429 | + {Opt_fd_buffered_io, "fd_buffered_io=%d"}, | |
| 410 | 430 | {Opt_err, NULL} |
| 411 | 431 | }; |
| 412 | 432 | |
| ... | ... | @@ -418,7 +438,7 @@ |
| 418 | 438 | struct fd_dev *fd_dev = se_dev->se_dev_su_ptr; |
| 419 | 439 | char *orig, *ptr, *arg_p, *opts; |
| 420 | 440 | substring_t args[MAX_OPT_ARGS]; |
| 421 | - int ret = 0, token; | |
| 441 | + int ret = 0, arg, token; | |
| 422 | 442 | |
| 423 | 443 | opts = kstrdup(page, GFP_KERNEL); |
| 424 | 444 | if (!opts) |
| ... | ... | @@ -459,6 +479,19 @@ |
| 459 | 479 | " bytes\n", fd_dev->fd_dev_size); |
| 460 | 480 | fd_dev->fbd_flags |= FBDF_HAS_SIZE; |
| 461 | 481 | break; |
| 482 | + case Opt_fd_buffered_io: | |
| 483 | + match_int(args, &arg); | |
| 484 | + if (arg != 1) { | |
| 485 | + pr_err("bogus fd_buffered_io=%d value\n", arg); | |
| 486 | + ret = -EINVAL; | |
| 487 | + goto out; | |
| 488 | + } | |
| 489 | + | |
| 490 | + pr_debug("FILEIO: Using buffered I/O" | |
| 491 | + " operations for struct fd_dev\n"); | |
| 492 | + | |
| 493 | + fd_dev->fbd_flags |= FDBD_HAS_BUFFERED_IO_WCE; | |
| 494 | + break; | |
| 462 | 495 | default: |
| 463 | 496 | break; |
| 464 | 497 | } |
| ... | ... | @@ -490,8 +523,10 @@ |
| 490 | 523 | ssize_t bl = 0; |
| 491 | 524 | |
| 492 | 525 | bl = sprintf(b + bl, "TCM FILEIO ID: %u", fd_dev->fd_dev_id); |
| 493 | - bl += sprintf(b + bl, " File: %s Size: %llu Mode: O_DSYNC\n", | |
| 494 | - fd_dev->fd_dev_name, fd_dev->fd_dev_size); | |
| 526 | + bl += sprintf(b + bl, " File: %s Size: %llu Mode: %s\n", | |
| 527 | + fd_dev->fd_dev_name, fd_dev->fd_dev_size, | |
| 528 | + (fd_dev->fbd_flags & FDBD_HAS_BUFFERED_IO_WCE) ? | |
| 529 | + "Buffered-WCE" : "O_DSYNC"); | |
| 495 | 530 | return bl; |
| 496 | 531 | } |
| 497 | 532 |