| Message ID | 1356537234-11507-3-git-send-email-piastry@etersoft.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 26 Dec 2012 19:53:53 +0400 Pavel Shilovsky <piastry@etersoft.ru> 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 writing directly to the server and then breaking oplock level from > level2 to None. > > Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS > and SMB2 protocols. > > Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> > --- > fs/cifs/file.c | 48 ++++++++++++++++++++---------------------------- > 1 file changed, 20 insertions(+), 28 deletions(-) > > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index 1b322d0..22c3725 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -2505,42 +2505,34 @@ 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; > > -#ifdef CONFIG_CIFS_SMB2 > - /* > - * 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. > - */ > - 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; > - > - return written; > + if (cinode->clientCanCacheAll) { > + 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); > } > -#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. > */ > - > - if (!cinode->clientCanCacheAll) > - return cifs_user_writev(iocb, iov, nr_segs, pos); > - > - 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); > + written = cifs_user_writev(iocb, iov, nr_segs, pos); > + if (written > 0 && cinode->clientCanCacheRead) { > + /* > + * Windows 7 server can delay breaking level2 oplock if a write > + * request comes - break it on the client to prevent reading > + * an old data. > + */ > + cifs_invalidate_mapping(inode); > + cFYI(1, "Set no oplock for inode=%p after a write operation", > + inode); > + cinode->clientCanCacheRead = false; In the above case, do we also need to inform the server that we're dropping the oplock here and that it doesn't need to be recalled? Is there a way to send an unsolicited "I'm dropping this oplock" to the server? Also, I'm still not 100% comfortable with the lack of locking around these clientCanCache* flags. It seems unlikely but could we end up racing with the grant of a CanCacheAll oplock here? > + } > + return written; > } > > static struct cifs_readdata * Looks like a much nicer scheme than you originally had. Even with the lack of locking around the CanCache* flags, I think this doesn't make things any worse. Reviewed-by: Jeff Layton <jlayton@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2013/1/1 Jeff Layton <jlayton@redhat.com>: > On Wed, 26 Dec 2012 19:53:53 +0400 > Pavel Shilovsky <piastry@etersoft.ru> 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 writing directly to the server and then breaking oplock level from >> level2 to None. >> >> Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS >> and SMB2 protocols. >> >> Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> >> --- >> fs/cifs/file.c | 48 ++++++++++++++++++++---------------------------- >> 1 file changed, 20 insertions(+), 28 deletions(-) >> >> diff --git a/fs/cifs/file.c b/fs/cifs/file.c >> index 1b322d0..22c3725 100644 >> --- a/fs/cifs/file.c >> +++ b/fs/cifs/file.c >> @@ -2505,42 +2505,34 @@ 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; >> >> -#ifdef CONFIG_CIFS_SMB2 >> - /* >> - * 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. >> - */ >> - 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; >> - >> - return written; >> + if (cinode->clientCanCacheAll) { >> + 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); >> } >> -#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. >> */ >> - >> - if (!cinode->clientCanCacheAll) >> - return cifs_user_writev(iocb, iov, nr_segs, pos); >> - >> - 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); >> + written = cifs_user_writev(iocb, iov, nr_segs, pos); >> + if (written > 0 && cinode->clientCanCacheRead) { >> + /* >> + * Windows 7 server can delay breaking level2 oplock if a write >> + * request comes - break it on the client to prevent reading >> + * an old data. >> + */ >> + cifs_invalidate_mapping(inode); >> + cFYI(1, "Set no oplock for inode=%p after a write operation", >> + inode); >> + cinode->clientCanCacheRead = false; > > In the above case, do we also need to inform the server > that we're dropping the oplock here and that it doesn't > need to be recalled? Is there a way to send an > unsolicited "I'm dropping this oplock" to the server? I don't think we have any possibilities to do this. Even if we try to break it on the server with an extra open request (with RequestOplock = 0) the server will send OplockBreak to this fid. > > Also, I'm still not 100% comfortable with the lack of > locking around these clientCanCache* flags. It seems > unlikely but could we end up racing with the grant of a > CanCacheAll oplock here? In SMB2.1 protocol this situation may happen. There are two possible scenarios: 1) we set CanCachRead to False, then open code sets both CanCache* values to true - seems no problem because we have already invalidated inode mapping - the next read will call readpages that will request a new data from the server. 2) open code sets both CanCache* values to true, then we set CanCacheRead to false - the only bad thing here is that we will not do pagereading that can hurt performance, but the data coherency should be fine. > >> + } >> + return written; >> } >> >> static struct cifs_readdata * > > Looks like a much nicer scheme than you originally had. Even with the > lack of locking around the CanCache* flags, I think this doesn't make > things any worse. > > Reviewed-by: Jeff Layton <jlayton@redhat.com> Thanks for reviewing these patches!
diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 1b322d0..22c3725 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2505,42 +2505,34 @@ 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; -#ifdef CONFIG_CIFS_SMB2 - /* - * 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. - */ - 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; - - return written; + if (cinode->clientCanCacheAll) { + 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); } -#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. */ - - if (!cinode->clientCanCacheAll) - return cifs_user_writev(iocb, iov, nr_segs, pos); - - 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); + written = cifs_user_writev(iocb, iov, nr_segs, pos); + if (written > 0 && cinode->clientCanCacheRead) { + /* + * Windows 7 server can delay breaking level2 oplock if a write + * request comes - break it on the client to prevent reading + * an old data. + */ + cifs_invalidate_mapping(inode); + cFYI(1, "Set no oplock for inode=%p after a write operation", + inode); + cinode->clientCanCacheRead = false; + } + return written; } static struct cifs_readdata *
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 writing directly to the server and then breaking oplock level from level2 to None. Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS and SMB2 protocols. Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> --- fs/cifs/file.c | 48 ++++++++++++++++++++---------------------------- 1 file changed, 20 insertions(+), 28 deletions(-)