On Thu, 6 Dec 2012 22:07:52 +0400 Pavel Shilovsky <[email protected]> wrote:
> If we have a read oplock and set a read lock in it, we can't write to the > locked area - so, filemap_fdatawrite may fail with a no information for a > userspace application even if we request a write to non-locked area. Fix > this by populating the page cache without marking affected pages dirty > after a successful write directly to the server. > > Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS > and SMB2 protocols. > > 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, 65 insertions(+), 31 deletions(-) > > diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c > index c6e32f2..210f0af 100644 > --- a/fs/cifs/cifsfs.c > +++ b/fs/cifs/cifsfs.c > @@ -229,6 +229,7 @@ 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 2ca6f7d..426a2bf 100644 > --- a/fs/cifs/cifsglob.h > +++ b/fs/cifs/cifsglob.h > @@ -1037,6 +1037,7 @@ 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 e2fabc9..84860f1 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -2109,7 +2109,15 @@ static int cifs_write_end(struct file *file, struct > address_space *mapping, > } else { > rc = copied; > pos += copied; > - set_page_dirty(page); > + /* > + * 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); > } > > if (rc > 0) { > @@ -2460,8 +2468,8 @@ ssize_t cifs_user_writev(struct kiocb *iocb, const > struct iovec *iov, > } > > static ssize_t > -cifs_writev(struct kiocb *iocb, const struct iovec *iov, > - unsigned long nr_segs, loff_t pos) > +cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov, > + unsigned long nr_segs, loff_t pos, bool cache_ex) > { > struct file *file = iocb->ki_filp; > struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data; > @@ -2483,8 +2491,12 @@ cifs_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); > + &iocb->ki_pos); > + if (!cache_ex) > + cinode->leave_pages_clean = false; > mutex_unlock(&inode->i_mutex); I guess the mutex lock should keep this from racing. > } > > @@ -2511,42 +2523,62 @@ 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); > - > -#ifdef CONFIG_CIFS_SMB2 > + ssize_t written, written2; > /* > - * 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. > + * 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 (!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; > + bool cache_ex = cinode->clientCanCacheAll; > + bool cache_read = cinode->clientCanCacheRead; > + int rc; > + loff_t saved_pos; > > - return written; > + 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); > } > -#endif > > /* > - * 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. > + * 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. > */ > + written = cifs_user_writev(iocb, iov, nr_segs, pos); > + if (!cache_read || written <= 0) > + return written; > > - if (!cinode->clientCanCacheAll) > - return cifs_user_writev(iocb, iov, nr_segs, pos); > - > + saved_pos = iocb->ki_pos; > + iocb->ki_pos = pos; > + /* we have a read oplock - need to store a data in the page cache */ > if (cap_unix(tcon->ses) && > - (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); > + ((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; > } > > static struct cifs_readdata * I can't help but wonder if there is some subtle raciness in how all of the canCache* flags are handled vs. pagecache vs. other operations. That said, I doubt this makes anything worse, so... 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
