The patch titled Subject: nbd: handle discard requests has been added to the -mm tree. Its filename is nbd-handle-discard-requests.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Paul Clements <paul.clements@xxxxxxxxxxxx> Subject: nbd: handle discard requests Add discard support to nbd. If the nbd-server supports discard, it will send NBD_FLAG_SEND_TRIM to the client. The client will then set the flag in the kernel via NBD_SET_FLAGS, which tells the kernel to enable discards for the device (QUEUE_FLAG_DISCARD). If discard support is enabled, then when the nbd client system receives a discard request, this will be passed along to the nbd-server. When the discard request is received by the nbd-server, it will perform: fallocate(.. FALLOC_FL_PUNCH_HOLE ..) To punch a hole in the backend storage, which is no longer needed. Signed-off-by: Paul Clements <paul.clements@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/block/nbd.c | 15 ++++++++++++++- include/linux/nbd.h | 6 +++++- 2 files changed, 19 insertions(+), 2 deletions(-) diff -puN drivers/block/nbd.c~nbd-handle-discard-requests drivers/block/nbd.c --- a/drivers/block/nbd.c~nbd-handle-discard-requests +++ a/drivers/block/nbd.c @@ -98,6 +98,7 @@ static const char *nbdcmd_to_ascii(int c case NBD_CMD_READ: return "read"; case NBD_CMD_WRITE: return "write"; case NBD_CMD_DISC: return "disconnect"; + case NBD_CMD_TRIM: return "trim/discard"; } return "invalid"; } @@ -461,7 +462,11 @@ static void nbd_handle_req(struct nbd_de nbd_cmd(req) = NBD_CMD_READ; if (rq_data_dir(req) == WRITE) { - nbd_cmd(req) = NBD_CMD_WRITE; + if ((req->cmd_flags & REQ_DISCARD)) { + WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM)); + nbd_cmd(req) = NBD_CMD_TRIM; + } else + nbd_cmd(req) = NBD_CMD_WRITE; if (nbd->flags & NBD_FLAG_READ_ONLY) { dev_err(disk_to_dev(nbd->disk), "Write on read-only\n"); @@ -667,6 +672,10 @@ static int __nbd_ioctl(struct block_devi mutex_unlock(&nbd->tx_lock); + if (nbd->flags & NBD_FLAG_SEND_TRIM) + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, + nbd->disk->queue); + thread = kthread_create(nbd_thread, nbd, nbd->disk->disk_name); if (IS_ERR(thread)) { mutex_lock(&nbd->tx_lock); @@ -684,6 +693,7 @@ static int __nbd_ioctl(struct block_devi nbd->file = NULL; nbd_clear_que(nbd); dev_warn(disk_to_dev(nbd->disk), "queue cleared\n"); + queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); if (file) fput(file); nbd->bytesize = 0; @@ -802,6 +812,9 @@ static int __init nbd_init(void) * Tell the block layer that we are not a rotational device */ queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue); + disk->queue->limits.discard_granularity = 512; + disk->queue->limits.max_discard_sectors = UINT_MAX; + disk->queue->limits.discard_zeroes_data = 0; } if (register_blkdev(NBD_MAJOR, "nbd")) { diff -puN include/linux/nbd.h~nbd-handle-discard-requests include/linux/nbd.h --- a/include/linux/nbd.h~nbd-handle-discard-requests +++ a/include/linux/nbd.h @@ -32,12 +32,16 @@ enum { NBD_CMD_READ = 0, NBD_CMD_WRITE = 1, - NBD_CMD_DISC = 2 + NBD_CMD_DISC = 2, + /* there is a gap here to match userspace */ + NBD_CMD_TRIM = 4 }; /* values for flags field */ #define NBD_FLAG_HAS_FLAGS (1 << 0) /* nbd-server supports flags */ #define NBD_FLAG_READ_ONLY (1 << 1) /* device is read-only */ +/* there is a gap here to match userspace */ +#define NBD_FLAG_SEND_TRIM (1 << 5) /* send trim/discard */ #define nbd_cmd(req) ((req)->cmd[0]) _ Patches currently in -mm which might be from paul.clements@xxxxxxxxxxxx are nbd-add-set-flags-ioctl.patch nbd-handle-discard-requests.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html