2011/4/12 Jeff Layton <jlayton@xxxxxxxxxx>:
> On Tue, 12 Apr 2011 13:43:07 +0400
> Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
>
>> 2011/4/2 Jeff Layton <jlayton@xxxxxxxxxx>:
>> > Add the ability for CIFS to do an asynchronous write. The kernel will
>> > set the frame up as it would for a "normal" SMBWrite2 request, and use
>> > cifs_call_async to send it. The mid callback will then be configured to
>> > handle the result.
>> >
>> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>> > ---
>> > fs/cifs/cifsproto.h | 19 +++++
>> > fs/cifs/cifssmb.c | 219 +++++++++++++++++++++++++++++++++++++++++++++++++++
>> > 2 files changed, 238 insertions(+), 0 deletions(-)
>>
>> Looks good too, except two small notes.
>>
>
> Thanks for looking. I respun this yesterday actually and the new patch
> is a bit different. With the new patchset, we'll no longer be
> constrained by the current wsize limit of 14 pages. It should be able
> to handle an arbitrary wsize, which should also help performance.
>
>
>> >
>> > diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
>> > index e255a2b..7b964df 100644
>> > --- a/fs/cifs/cifsproto.h
>> > +++ b/fs/cifs/cifsproto.h
>> > @@ -21,6 +21,7 @@
>> > #ifndef _CIFSPROTO_H
>> > #define _CIFSPROTO_H
>> > #include <linux/nls.h>
>> > +#include <linux/pagevec.h>
>> >
>> > struct statfs;
>> > struct smb_vol;
>> > @@ -433,4 +434,22 @@ extern int mdfour(unsigned char *, unsigned char *, int);
>> > extern int E_md4hash(const unsigned char *passwd, unsigned char *p16);
>> > extern int SMBencrypt(unsigned char *passwd, const unsigned char *c8,
>> > unsigned char *p24);
>> > +
>> > +/* asynchronous write support */
>> > +struct cifs_writedata {
>> > + struct list_head pending;
>> > + struct kref refcount;
>> > + struct completion completion;
>> > + struct work_struct work;
>> > + struct cifsFileInfo *cfile;
>> > + __u64 offset;
>> > + unsigned int bytes;
>> > + int result;
>> > + struct page *pages[PAGEVEC_SIZE];
>> > +};
>> > +
>> > +int cifs_async_writev(struct cifs_writedata *wdata);
>> > +struct cifs_writedata *cifs_writedata_alloc(void);
>> > +void cifs_writedata_release(struct kref *refcount);
>> > +
>> > #endif /* _CIFSPROTO_H */
>> > diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
>> > index 8de7e79..b308605 100644
>> > --- a/fs/cifs/cifssmb.c
>> > +++ b/fs/cifs/cifssmb.c
>> > @@ -32,6 +32,7 @@
>> > #include <linux/vfs.h>
>> > #include <linux/slab.h>
>> > #include <linux/posix_acl_xattr.h>
>> > +#include <linux/pagemap.h>
>> > #include <asm/uaccess.h>
>> > #include "cifspdu.h"
>> > #include "cifsglob.h"
>> > @@ -1604,6 +1605,224 @@ CIFSSMBWrite(const int xid, struct cifs_tcon *tcon,
>> > return rc;
>> > }
>> >
>> > +void
>> > +cifs_writedata_release(struct kref *refcount)
>> > +{
>> > + struct cifs_writedata *wdata = container_of(refcount,
>> > + struct cifs_writedata, refcount);
>> > + struct address_space *mapping;
>> > +
>> > + if (wdata->cfile) {
>> > + mapping = wdata->cfile->dentry->d_inode->i_mapping;
>> > +
>> > + spin_lock(&mapping->private_lock);
>> > + list_del(&wdata->pending);
>> > + spin_unlock(&mapping->private_lock);
>> > +
>> > + cifsFileInfo_put(wdata->cfile);
>> > + }
>> > +
>> > + kfree(wdata);
>> > +}
>> > +
>> > +static void
>> > +cifs_writev_complete(struct work_struct *work)
>> > +{
>> > + struct cifs_writedata *wdata = container_of(work,
>> > + struct cifs_writedata, work);
>> > + struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
>> ^^^ this variable is unused.
>>
> Not exactly.
>
>> > + struct inode *inode = wdata->cfile->dentry->d_inode;
>> > + struct page *page;
>> > + int i = 0;
>> > +
>> > + if (wdata->result == 0) {
>> > + cifs_update_eof(CIFS_I(inode), wdata->offset, wdata->bytes);
>> > + cifs_stats_bytes_written(tcon, wdata->bytes);
> ^^^^^
> The tcon is used here
Strange, the compiler (gcc-4.4.4-1ubuntu2) reports it:
/home/piastry/git/cifs-2.6/fs/cifs/cifssmb.c: In function
‘cifs_writev_complete’:
/home/piastry/git/cifs-2.6/fs/cifs/cifssmb.c:1633: warning: unused
variable ‘tcon’
but you are right - it is used.
>> > + }
>> > +
>> > + for (i = 0; i < ARRAY_SIZE(wdata->pages) && (page = wdata->pages[i]);
>> > + i++) {
>> > + if (wdata->result == -EAGAIN)
>> > + __set_page_dirty_nobuffers(page);
>> > + else if (wdata->result < 0)
>> > + SetPageError(page);
>> > + end_page_writeback(page);
>> > + page_cache_release(page);
>> > + }
>> > + if (wdata->result != -EAGAIN)
>> > + mapping_set_error(inode->i_mapping, wdata->result);
>> > + complete(&wdata->completion);
>> > + kref_put(&wdata->refcount, cifs_writedata_release);
>> > +}
>> > +
>> > +struct cifs_writedata *
>> > +cifs_writedata_alloc(void)
>> > +{
>> > + struct cifs_writedata *wdata;
>> > +
>> > + wdata = kzalloc(sizeof(*wdata), GFP_NOFS);
>> > + if (wdata != NULL) {
>> > + INIT_LIST_HEAD(&wdata->pending);
>> > + INIT_WORK(&wdata->work, cifs_writev_complete);
>> > + kref_init(&wdata->refcount);
>> > + init_completion(&wdata->completion);
>> > + }
>> > + return wdata;
>> > +}
>> > +
>> > +/*
>> > + * Check the midState and signature on received buffer (if any), and queue the
>> > + * workqueue completion task.
>> > + */
>> > +static void
>> > +cifs_writev_callback(struct mid_q_entry *mid)
>> > +{
>> > + struct cifs_writedata *wdata = mid->callback_data;
>> > + struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
>> > + unsigned int written;
>> > + WRITE_RSP *smb = (WRITE_RSP *)mid->resp_buf;
>> > +
>> > + switch(mid->midState) {
>> > + case MID_RESPONSE_RECEIVED:
>> > + wdata->result = cifs_check_receive(mid, tcon->ses->server, 0);
>> > + if (wdata->result != 0)
>> > + break;
>> > +
>> > + written = le16_to_cpu(smb->CountHigh);
>> > + written <<= 16;
>> > + written += le16_to_cpu(smb->Count);
>> > + /*
>> > + * Mask off high 16 bits when bytes written as returned
>> > + * by the server is greater than bytes requested by the
>> > + * client. OS/2 servers are known to set incorrect
>> > + * CountHigh values.
>> > + */
>> > + if (written > wdata->bytes)
>> > + written &= 0xFFFF;
>> > +
>> > + if (written < wdata->bytes)
>> > + wdata->result = -ENOSPC;
>> > + else
>> > + wdata->bytes = written;
>> > + break;
>> > + case MID_REQUEST_SUBMITTED:
>> > + case MID_RETRY_NEEDED:
>> > + wdata->result = -EAGAIN;
>> > + break;
>> > + default:
>> > + wdata->result = -EIO;
>> > + break;
>> > + }
>> > +
>> > + queue_work(system_nrt_wq, &wdata->work);
>> > + DeleteMidQEntry(mid);
>> > + atomic_dec(&tcon->ses->server->inFlight);
>> > + wake_up(&tcon->ses->server->request_q);
>> > +}
>> > +
>> > +/* cifs_async_writev - send an async write, and set up mid to handle result */
>> > +int
>> > +cifs_async_writev(struct cifs_writedata *wdata)
>> > +{
>> > + int i, rc = -EACCES;
>> > + WRITE_REQ *smb = NULL;
>> > + int wct;
>> > + struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
>> > + struct inode *inode = wdata->cfile->dentry->d_inode;
>> > + unsigned int npages = ARRAY_SIZE(wdata->pages);
>> > + struct kvec *iov = NULL;
>> > +
>> > + cFYI(1, "async write at %llu %u bytes", wdata->offset, wdata->bytes);
>> ^^^^ bytes is
>> zero here. You calculate it next - I suggest to move this info message
>> after you get right bytes value.
>>
>
> Good catch. Will fix.
>
>> > +
>> > + if (tcon->ses->capabilities & CAP_LARGE_FILES) {
>> > + wct = 14;
>> > + } else {
>> > + wct = 12;
>> > + if (wdata->offset >> 32 > 0) {
>> > + /* can not handle big offset for old srv */
>> > + return -EIO;
>> > + }
>> > + }
>> > +
>> > + rc = small_smb_init(SMB_COM_WRITE_ANDX, wct, tcon, (void **)&smb);
>> > + if (rc)
>> > + goto async_writev_out;
>> > +
>> > + /* FIXME: only allocate number of kvecs we need */
>> > + iov = kzalloc((npages + 1) * sizeof(*iov), GFP_NOFS);
>> > + if (iov == NULL) {
>> > + rc = -ENOMEM;
>> > + goto async_writev_out;
>> > + }
>> > +
>> > + smb->AndXCommand = 0xFF; /* none */
>> > + smb->Fid = wdata->cfile->netfid;
>> > + smb->OffsetLow = cpu_to_le32(wdata->offset & 0xFFFFFFFF);
>> > + if (wct == 14)
>> > + smb->OffsetHigh = cpu_to_le32(wdata->offset >> 32);
>> > + smb->Reserved = 0xFFFFFFFF;
>> > + smb->WriteMode = 0;
>> > + smb->Remaining = 0;
>> > +
>> > + smb->DataOffset =
>> > + cpu_to_le16(offsetof(struct smb_com_write_req, Data) - 4);
>> > +
>> > + /* 4 for RFC1001 length + 1 for BCC */
>> > + iov[0].iov_len = be32_to_cpu(smb->hdr.smb_buf_length) + 4 + 1;
>> > + iov[0].iov_base = smb;
>> > +
>> > + /* marshal up the pages into iov array */
>> > + npages = 0;
>> > + wdata->bytes = 0;
>> > + for (i = 0; i < ARRAY_SIZE(wdata->pages) && wdata->pages[i]; i++) {
>> > + if (wdata->bytes + PAGE_CACHE_SIZE <=
>> > + CIFS_SB(inode->i_sb)->wsize) {
>> > + iov[i + 1].iov_len = min(inode->i_size -
>> > + page_offset(wdata->pages[i]),
>> > + (loff_t)PAGE_CACHE_SIZE);
>> > + iov[i + 1].iov_base = kmap(wdata->pages[i]);
>> > + wdata->bytes += iov[i + 1].iov_len;
>> > + npages++;
>> > + } else {
>> > + /* if we're beyond wsize, then re-mark page dirty */
>> > + __set_page_dirty_nobuffers(wdata->pages[i]);
>> > + }
>> > + }
>> > +
>> > + smb->DataLengthLow = cpu_to_le16(wdata->bytes & 0xFFFF);
>> > + smb->DataLengthHigh = cpu_to_le16(wdata->bytes >> 16);
>> > +
>> > + if (wct == 14) {
>> > + inc_rfc1001_len(&smb->hdr, wdata->bytes + 1);
>> > + put_bcc(wdata->bytes + 1, &smb->hdr);
>> > + } else {
>> > + /* wct == 12 */
>> > + struct smb_com_writex_req *smbw =
>> > + (struct smb_com_writex_req *)smb;
>> > + inc_rfc1001_len(&smbw->hdr, wdata->bytes + 5);
>> > + put_bcc(wdata->bytes + 5, &smbw->hdr);
>> > + iov[0].iov_len += 4; /* pad bigger by four bytes */
>> > + }
>> > +
>> > + kref_get(&wdata->refcount);
>> > + rc = cifs_call_async(tcon->ses->server, iov, npages + 1,
>> > + cifs_writev_callback, wdata);
>> > +
>> > + if (rc == 0)
>> > + cifs_stats_inc(&tcon->stats.cifs_stats.num_writes);
>> > + else
>> > + kref_put(&wdata->refcount, cifs_writedata_release);
>> > +
>> > + /* send is done, unmap pages */
>> > + for (i = 0; i < npages; i++)
>> > + kunmap(wdata->pages[i]);
>> > +
>> > +async_writev_out:
>> > + cifs_small_buf_release(smb);
>> > + kfree(iov);
>> > + return rc;
>> > +}
>> > +
>> > int
>> > CIFSSMBWrite2(const int xid, struct cifs_tcon *tcon,
>> > const int netfid, const unsigned int count,
>> > --
>> > 1.7.4
>> >
>> > --
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>> > the body of a message to majordomo@xxxxxxxxxxxxxxx
>> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>> >
>>
>> Anyway, it's good. You can my "Reviewed-by: Pavel Shilovsky
>> <piastry@xxxxxxxxxxx>" tag when you fix the notes above.
>>
>
>
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
>
--
Best regards,
Pavel Shilovsky.
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