2010/12/14 Jeff Layton <jlayton@xxxxxxxxxx>:
> On Tue, 14 Dec 2010 14:10:58 +0300
> Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
>
>> If we don't have Exclusive oplock we write a data to the server through
>> cifs_write. Also set invalidate_mapping flag on the inode if we wrote
>> something to the server.
>>
>> Signed-off-by: Pavel Shilovsky <piastryyy@xxxxxxxxx>
>> ---
>> fs/cifs/cifsfs.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++---
>> fs/cifs/cifsproto.h | 3 ++
>> fs/cifs/file.c | 5 +--
>> 3 files changed, 75 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
>> index a218afe..5df0503 100644
>> --- a/fs/cifs/cifsfs.c
>> +++ b/fs/cifs/cifsfs.c
>> @@ -572,15 +572,81 @@ cifs_do_mount(struct file_system_type *fs_type,
>> return dget(sb->s_root);
>> }
>>
>> +static ssize_t cifs_strict_write(struct kiocb *iocb, const struct iovec *iov,
>> + unsigned long nr_segs, loff_t pos)
>> +{
>> + struct inode *inode;
>> + struct cifs_sb_info *cifs_sb;
>> + ssize_t written = 0;
>> + unsigned long i, len = 0;
>> + char *buf, *offset;
>> +
>> + inode = iocb->ki_filp->f_path.dentry->d_inode;
>> +
>> + if (CIFS_I(inode)->clientCanCacheAll)
>> + return generic_file_aio_write(iocb, iov, nr_segs, pos);
>> +
>> + cifs_sb = CIFS_SB(iocb->ki_filp->f_path.dentry->d_sb);
>> +
>> + /*
>> + * In strict cache mode we need to write the data to the server exactly
>> + * from the pos to pos+len-1 rather than flush all affected pages
>> + * because it may cause a error with mandatory locks on these pages but
>> + * not on the region from pos to ppos+len-1.
>> + */
>> +
>> + for (i = 0; i < nr_segs; i++)
>> + len += iov[i].iov_len;
>> +
>> + /*
>> + * BB - optimize the way when signing is disabled. We can drop this
>> + * extra memory-to-memory copying and use iovec buffers for constructing
>> + * write request.
>> + */
>> +
>> + buf = kmalloc(len, GFP_KERNEL);
>> +
>
> Actually...I thought about another problem here. Suppose an application
> does a 100M write. This may fail in that case. It varies by the slab
> allocator in use, but there are limits to how large you can kmalloc.
> This is especially going to be a problem on 32-bit arches where
> GFP_KERNEL memory is more limited.
>
> There are a couple of different solutions, but I think the best one
> would be to stitch together individual pages. Walk the iov array first
> and figure out how many pages you're going to need, and kmalloc an iov
> array that size. Then start allocating pages (preferably using
> GFP_HIGHMEM and kmapping them) and then copy the data to them. Stop
> when you get to the wsize limit, and issue a CIFSSMBWrite2 call. When
> it returns, pick up where you left off and do it again.
May be I should allocate buffer of min(wsize, write_len) size, fill it
with a data to write on cycle and issue a cifs_write with this buffer.
1) get write data len into 'len'
2) buf = kmalloc(min(wsize, len), GFP_KERNEL)
3) last_ind = 0, last_len = iov[0].iov_len
4) while (len > 0){
cur_len = min(len, last_len)
memcpy(buf, iov[last_ind].iov_base + iov[last_ind].iov_len -
last_len, cur_len)
len -= cur_len
last_len -= cur_len
if (last_len == 0) {
last_ind++
last_len = iov[last_ind].iov_len
}
cifs_write(buf)
}
So - it is like the way I do in read part (cifs_fill_iov). Thoughts?
>
>> + for (i = 0, offset = buf; i < nr_segs; i++) {
>> + if (copy_from_user(offset, iov[i].iov_base, iov[i].iov_len)) {
>> + kfree(buf);
>> + return -EFAULT;
>> + }
>> +
>> + offset += iov[i].iov_len;
>> + }
>> +
>> + written = cifs_write((struct cifsFileInfo *)iocb->ki_filp->private_data,
>> + buf, len, &pos);
>> + if (written < 0) {
>> + kfree(buf);
>> + return written;
>> + }
>> +
>> + iocb->ki_pos = pos;
>> +
>> + if (written > 0)
>> + CIFS_I(inode)->invalid_mapping = true;
>> +
>> + kfree(buf);
>> + return written;
>> +}
>> +
>> static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
>> unsigned long nr_segs, loff_t pos)
>> {
>> struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
>> ssize_t written;
>> + int rc;
>>
>> written = generic_file_aio_write(iocb, iov, nr_segs, pos);
>> - if (!CIFS_I(inode)->clientCanCacheAll)
>> - filemap_fdatawrite(inode->i_mapping);
>> +
>> + if (CIFS_I(inode)->clientCanCacheAll)
>> + return written;
>> +
>> + rc = filemap_fdatawrite(inode->i_mapping);
>> + if (rc)
>> + cFYI(1, "cifs_file_aio_write: %d rc on %p inode", rc, inode);
>> +
>> return written;
>> }
>>
>> @@ -714,7 +780,7 @@ const struct file_operations cifs_file_strict_ops = {
>> .read = do_sync_read,
>> .write = do_sync_write,
>> .aio_read = generic_file_aio_read,
>> - .aio_write = cifs_file_aio_write,
>> + .aio_write = cifs_strict_write,
>> .open = cifs_open,
>> .release = cifs_close,
>> .lock = cifs_lock,
>> @@ -770,7 +836,7 @@ const struct file_operations cifs_file_strict_nobrl_ops = {
>> .read = do_sync_read,
>> .write = do_sync_write,
>> .aio_read = generic_file_aio_read,
>> - .aio_write = cifs_file_aio_write,
>> + .aio_write = cifs_strict_write,
>> .open = cifs_open,
>> .release = cifs_close,
>> .fsync = cifs_strict_fsync,
>> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
>> index e6d1481..3a337a9 100644
>> --- a/fs/cifs/cifsproto.h
>> +++ b/fs/cifs/cifsproto.h
>> @@ -79,6 +79,9 @@ extern int checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length);
>> extern bool is_valid_oplock_break(struct smb_hdr *smb,
>> struct TCP_Server_Info *);
>> extern bool is_size_safe_to_change(struct cifsInodeInfo *, __u64 eof);
>> +extern ssize_t cifs_write(struct cifsFileInfo *open_file,
>> + const char *write_data, size_t write_size,
>> + loff_t *poffset);
>> extern struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *, bool);
>> extern struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *, bool);
>> extern unsigned int smbCalcSize(struct smb_hdr *ptr);
>> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>> index dd1e59a..2c848ef 100644
>> --- a/fs/cifs/file.c
>> +++ b/fs/cifs/file.c
>> @@ -1026,9 +1026,8 @@ ssize_t cifs_user_write(struct file *file, const char __user *write_data,
>> return total_written;
>> }
>>
>> -static ssize_t cifs_write(struct cifsFileInfo *open_file,
>> - const char *write_data, size_t write_size,
>> - loff_t *poffset)
>> +ssize_t cifs_write(struct cifsFileInfo *open_file, const char *write_data,
>> + size_t write_size, loff_t *poffset)
>> {
>> int rc = 0;
>> unsigned int bytes_written = 0;
>
>
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
>
--
Best regards,
Pavel Shilovsky.
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