On Wed, 26 Dec 2012 19:53:52 +0400 Pavel Shilovsky <[email protected]> wrote:
> that solution has data races and can end up two identical writes to the > server: when clientCanCacheAll value can be changed during the execution > of __generic_file_aio_write. > > Signed-off-by: Pavel Shilovsky <[email protected]> > --- > fs/cifs/cifsfs.c | 1 - > fs/cifs/cifsglob.h | 1 - > fs/cifs/file.c | 94 > ++++++++++++++++++------------------------------------ > 3 files changed, 31 insertions(+), 65 deletions(-) > > diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c > index f653835..de7f916 100644 > --- a/fs/cifs/cifsfs.c > +++ b/fs/cifs/cifsfs.c > @@ -228,7 +228,6 @@ cifs_alloc_inode(struct super_block *sb) > cifs_set_oplock_level(cifs_inode, 0); > cifs_inode->delete_pending = false; > cifs_inode->invalid_mapping = false; > - cifs_inode->leave_pages_clean = false; > cifs_inode->vfs_inode.i_blkbits = 14; /* 2**14 = CIFS_MAX_MSGSIZE */ > cifs_inode->server_eof = 0; > cifs_inode->uniqueid = 0; > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h > index aea1eec..dfab450 100644 > --- a/fs/cifs/cifsglob.h > +++ b/fs/cifs/cifsglob.h > @@ -1030,7 +1030,6 @@ struct cifsInodeInfo { > bool clientCanCacheAll; /* read and writebehind oplock */ > bool delete_pending; /* DELETE_ON_CLOSE is set */ > bool invalid_mapping; /* pagecache is invalid */ > - bool leave_pages_clean; /* protected by i_mutex, not set pages dirty */ > unsigned long time; /* jiffies of last update of inode */ > u64 server_eof; /* current file size on server -- > protected by i_lock */ > u64 uniqueid; /* server inode number */ > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index 0a6677b..1b322d0 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -2103,15 +2103,7 @@ static int cifs_write_end(struct file *file, struct > address_space *mapping, > } else { > rc = copied; > pos += copied; > - /* > - * When we use strict cache mode and cifs_strict_writev was run > - * with level II oplock (indicated by leave_pages_clean field of > - * CIFS_I(inode)), we can leave pages clean - cifs_strict_writev > - * sent the data to the server itself. > - */ > - if (!CIFS_I(inode)->leave_pages_clean || > - !(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO)) > - set_page_dirty(page); > + set_page_dirty(page); > } > > if (rc > 0) { > @@ -2462,8 +2454,8 @@ ssize_t cifs_user_writev(struct kiocb *iocb, const > struct iovec *iov, > } > > static ssize_t > -cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov, > - unsigned long nr_segs, loff_t pos, bool cache_ex) > +cifs_writev(struct kiocb *iocb, const struct iovec *iov, > + unsigned long nr_segs, loff_t pos) > { > struct file *file = iocb->ki_filp; > struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data; > @@ -2485,12 +2477,8 @@ cifs_pagecache_writev(struct kiocb *iocb, const struct > iovec *iov, > server->vals->exclusive_lock_type, NULL, > CIFS_WRITE_OP)) { > mutex_lock(&inode->i_mutex); > - if (!cache_ex) > - cinode->leave_pages_clean = true; > rc = __generic_file_aio_write(iocb, iov, nr_segs, > - &iocb->ki_pos); > - if (!cache_ex) > - cinode->leave_pages_clean = false; > + &iocb->ki_pos); > mutex_unlock(&inode->i_mutex); > } > > @@ -2517,62 +2505,42 @@ cifs_strict_writev(struct kiocb *iocb, const struct > iovec *iov, > struct cifsFileInfo *cfile = (struct cifsFileInfo *) > iocb->ki_filp->private_data; > struct cifs_tcon *tcon = tlink_tcon(cfile->tlink); > - ssize_t written, written2; > + > +#ifdef CONFIG_CIFS_SMB2 > /* > - * We need to store clientCanCacheAll here to prevent race > - * conditions - this value can be changed during an execution > - * of generic_file_aio_write. For CIFS it can be changed from > - * true to false only, but for SMB2 it can be changed both from > - * true to false and vice versa. So, we can end up with a data > - * stored in the cache, not marked dirty and not sent to the > - * server if this value changes its state from false to true > - * after cifs_write_end. > + * If we have an oplock for read and want to write a data to the file > + * we need to store it in the page cache and then push it to the server > + * to be sure the next read will get a valid data. > */ > - bool cache_ex = cinode->clientCanCacheAll; > - bool cache_read = cinode->clientCanCacheRead; > - int rc; > - loff_t saved_pos; > + if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) { > + ssize_t written; > + int rc; > + > + written = generic_file_aio_write(iocb, iov, nr_segs, pos); > + rc = filemap_fdatawrite(inode->i_mapping); > + if (rc) > + return (ssize_t)rc; > > - if (cache_ex) { > - if (cap_unix(tcon->ses) && > - ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) && > - (CIFS_UNIX_FCNTL_CAP & le64_to_cpu( > - tcon->fsUnixInfo.Capability))) > - return generic_file_aio_write(iocb, iov, nr_segs, pos); > - return cifs_pagecache_writev(iocb, iov, nr_segs, pos, cache_ex); > + return written; > } > +#endif > > /* > - * For files without exclusive oplock 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 non-oplocked files 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. > */ > - written = cifs_user_writev(iocb, iov, nr_segs, pos); > - if (!cache_read || written <= 0) > - return written; > > - saved_pos = iocb->ki_pos; > - iocb->ki_pos = pos; > - /* we have a read oplock - need to store a data in the page cache */ > + if (!cinode->clientCanCacheAll) > + return cifs_user_writev(iocb, iov, nr_segs, pos); > + > if (cap_unix(tcon->ses) && > - ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) && > - (CIFS_UNIX_FCNTL_CAP & le64_to_cpu( > - tcon->fsUnixInfo.Capability))) > - written2 = generic_file_aio_write(iocb, iov, nr_segs, pos); > - else > - written2 = cifs_pagecache_writev(iocb, iov, nr_segs, pos, > - cache_ex); > - /* errors occured during writing - invalidate the page cache */ > - if (written2 < 0) { > - rc = cifs_invalidate_mapping(inode); > - if (rc) > - written = (ssize_t)rc; > - else > - iocb->ki_pos = saved_pos; > - } > - return written; > + (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) && > + ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) > + return generic_file_aio_write(iocb, iov, nr_segs, pos); > + > + return cifs_writev(iocb, iov, nr_segs, pos); > } > > static struct cifs_readdata * Straightforward... Acked-by: Jeff Layton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
