From patchwork Tue Mar 1 06:38:50 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aneesh Kumar K.V" X-Patchwork-Id: 84907 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 1D2AAB7157 for ; Tue, 1 Mar 2011 18:00:36 +1100 (EST) Received: from localhost ([127.0.0.1]:46527 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PuJZQ-000645-8C for incoming@patchwork.ozlabs.org; Tue, 01 Mar 2011 02:00:32 -0500 Received: from [140.186.70.92] (port=39230 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PuJEx-0007dP-QC for qemu-devel@nongnu.org; Tue, 01 Mar 2011 01:39:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PuJEu-00035n-JE for qemu-devel@nongnu.org; Tue, 01 Mar 2011 01:39:23 -0500 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:35875) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PuJEu-00035J-0O for qemu-devel@nongnu.org; Tue, 01 Mar 2011 01:39:20 -0500 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [202.81.31.246]) by e23smtp09.au.ibm.com (8.14.4/8.13.1) with ESMTP id p216d5b7013672 for ; Tue, 1 Mar 2011 17:39:05 +1100 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p216d5tI2232328 for ; Tue, 1 Mar 2011 17:39:05 +1100 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p216d4uX025601 for ; Tue, 1 Mar 2011 17:39:05 +1100 Received: from skywalker.ibm.com ([9.126.239.109]) by d23av01.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id p216cxQd025425; Tue, 1 Mar 2011 17:39:02 +1100 From: "Aneesh Kumar K.V" To: qemu-devel@nongnu.org Date: Tue, 1 Mar 2011 12:08:50 +0530 Message-Id: <1298961534-8099-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1298961534-8099-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1298961534-8099-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6, seldom 2.4 (older, 4) X-Received-From: 202.81.31.142 Cc: aliguori@us.ibm.com, "Aneesh Kumar K.V" Subject: [Qemu-devel] [PATCH -V2 2/6] hw/9pfs: Add file descriptor reclaim support X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Signed-off-by: Aneesh Kumar K.V --- hw/9pfs/virtio-9p.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++-- 1 files changed, 95 insertions(+), 4 deletions(-) diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c index a9f52c6..811ac38 100644 --- a/hw/9pfs/virtio-9p.c +++ b/hw/9pfs/virtio-9p.c @@ -20,6 +20,7 @@ #include "virtio-9p-xattr.h" int debug_9p_pdu; +static void v9fs_reclaim_fd(V9fsState *s); enum { Oread = 0x00, @@ -107,7 +108,12 @@ static int v9fs_do_closedir(V9fsState *s, DIR *dir) static int v9fs_do_open(V9fsState *s, V9fsString *path, int flags) { - return s->ops->open(&s->ctx, path->data, flags); + int fd; + fd = s->ops->open(&s->ctx, path->data, flags); + if (fd > P9_FD_RECLAIM_THRES) { + v9fs_reclaim_fd(s); + } + return fd; } static DIR *v9fs_do_opendir(V9fsState *s, V9fsString *path) @@ -188,6 +194,7 @@ static int v9fs_do_fstat(V9fsState *s, int fd, struct stat *stbuf) static int v9fs_do_open2(V9fsState *s, char *fullname, uid_t uid, gid_t gid, int flags, int mode) { + int fd; FsCred cred; cred_init(&cred); @@ -196,7 +203,11 @@ static int v9fs_do_open2(V9fsState *s, char *fullname, uid_t uid, gid_t gid, cred.fc_mode = mode & 07777; flags = flags; - return s->ops->open2(&s->ctx, fullname, flags, &cred); + fd = s->ops->open2(&s->ctx, fullname, flags, &cred); + if (fd > P9_FD_RECLAIM_THRES) { + v9fs_reclaim_fd(s); + } + return fd; } static int v9fs_do_symlink(V9fsState *s, V9fsFidState *fidp, @@ -434,6 +445,23 @@ static V9fsFidState *lookup_fid(V9fsState *s, int32_t fid) for (f = s->fid_list; f; f = f->next) { if (f->fid == fid) { + /* + * check whether we need to reopen the + * file. We might have closed the fd + * while trying to free up some file + * descriptors. + */ + if (f->fsmap.fid_type == P9_FID_FILE) { + /* FIXME!! should we remember the open flags ?*/ + if (f->fsmap.fs.fd == -1) { + f->fsmap.fs.fd = v9fs_do_open(s, &f->fsmap.path, O_RDWR); + } + } + /* + * Mark the fid as referenced so that the LRU + * reclaim won't close the file descriptor + */ + f->fsmap.flags |= FID_REFERENCED; return f; } } @@ -461,6 +489,62 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid) return f; } +static void v9fs_reclaim_fd(V9fsState *s) +{ + int reclaim_count = 0; + V9fsFidState *f; + + for (f = s->fid_list; f; f = f->next) { + /* + * Unlink fids cannot be reclaimed. Check + * for them and skip them + */ + if (f->fsmap.flags & FID_NON_RECLAIMABLE) { + continue; + } + /* + * if it is a recently referenced fid + * we leave the fid untouched and clear the + * reference bit. We come back to it later + * in the next iteration. (a simple LRU without + * moving list elements around) + */ + if (f->fsmap.flags & FID_REFERENCED) { + f->fsmap.flags &= ~FID_REFERENCED; + continue; + } + /* + * reclaim fd, by closing the file descriptors + */ + if (f->fsmap.fid_type == P9_FID_FILE) { + if (f->fsmap.fs.fd != -1) { + v9fs_do_close(s, f->fsmap.fs.fd); + f->fsmap.fs.fd = -1; + reclaim_count++; + } + } + if (reclaim_count >= P9_FD_RECLAIM_THRES/2) { + break; + } + } +} + +static void v9fs_mark_fids_unreclaim(V9fsState *s, V9fsString *str) +{ + V9fsFidState *fidp; + for (fidp = s->fid_list; fidp; fidp = fidp->next) { + if (!strcmp(fidp->fsmap.path.data, str->data)) { + /* Mark the fid non reclaimable. */ + fidp->fsmap.flags |= FID_NON_RECLAIMABLE; + /* reopen the file if already closed */ + if (fidp->fsmap.fs.fd == -1) { + fidp->fsmap.fs.fd = v9fs_do_open(s, &fidp->fsmap.path, O_RDWR); + } + } + } +} + + static int v9fs_xattr_fid_clunk(V9fsState *s, V9fsFidState *fidp) { int retval = 0; @@ -516,7 +600,10 @@ static int free_fid(V9fsState *s, int32_t fid) *fidpp = fidp->next; if (fidp->fsmap.fid_type == P9_FID_FILE) { - v9fs_do_close(s, fidp->fsmap.fs.fd); + /* I we reclaimed the fd no need to close */ + if (fidp->fsmap.fs.fd != -1) { + v9fs_do_close(s, fidp->fsmap.fs.fd); + } } else if (fidp->fsmap.fid_type == P9_FID_DIR) { v9fs_do_closedir(s, fidp->fsmap.fs.dir); } else if (fidp->fsmap.fid_type == P9_FID_XATTR) { @@ -2719,7 +2806,11 @@ static void v9fs_remove(V9fsState *s, V9fsPDU *pdu) err = -EINVAL; goto out; } - + /* + * IF the file is unlinked, we cannot reopen + * the file later. So don't reclaim fd + */ + v9fs_mark_fids_unreclaim(s, &vs->fidp->fsmap.path); err = v9fs_do_remove(s, &vs->fidp->fsmap.path); v9fs_remove_post_remove(s, vs, err); return;