Date: Mon, 13 Feb 2023 22:31:43 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 0152d453a08f - main - msdosfs deextend: validate pages of the partial buffer Message-ID: <202302132231.31DMVhCv080775@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=0152d453a08fa2bad694dc04a8184fce2b7faa10 commit 0152d453a08fa2bad694dc04a8184fce2b7faa10 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2023-02-11 18:09:30 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-02-13 22:29:42 +0000 msdosfs deextend: validate pages of the partial buffer Suppose that the cluster size is larger than page size. If the buffer at the old EOF (before extending) was partial and dirty, it cannot be automatically neither written out nor validated by the buffer cache, since extending buffer adds invalid pages at the end. Correct the buffer state by calling vfs_bio_clrbuf() on it, to mark newly added and zeroed pages as valid. Note that UFS is immune to the problem because ffs_truncate() always allocate the block and buffer for the last byte of the file. PR: 269341 Reported by: asomers In collaboration with: pho Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D38549 --- sys/fs/msdosfs/msdosfs_denode.c | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-) diff --git a/sys/fs/msdosfs/msdosfs_denode.c b/sys/fs/msdosfs/msdosfs_denode.c index 0b4135d60784..a82517acbdfe 100644 --- a/sys/fs/msdosfs/msdosfs_denode.c +++ b/sys/fs/msdosfs/msdosfs_denode.c @@ -497,6 +497,7 @@ deextend(struct denode *dep, u_long length, struct ucred *cred) { struct msdosfsmount *pmp = dep->de_pmp; struct vnode *vp = DETOV(dep); + struct buf *bp; u_long count; int error; @@ -523,16 +524,41 @@ deextend(struct denode *dep, u_long length, struct ucred *cred) if (count > pmp->pm_freeclustercount) return (ENOSPC); error = extendfile(dep, count, NULL, NULL, DE_CLEAR); - if (error) { - /* truncate the added clusters away again */ - (void) detrunc(dep, dep->de_FileSize, 0, cred); - return (error); - } + if (error != 0) + goto rewind; } + + /* + * For the case of cluster size larger than the page size, we + * need to ensure that the possibly dirty partial buffer at + * the old end of file is not filled with invalid pages by + * extension. Otherwise it has a contradictory state of + * B_CACHE | B_DELWRI but with invalid pages, and cannot be + * neither written out nor validated. + * + * Fix it by proactively clearing extended pages. + */ + error = bread(vp, de_cluster(pmp, dep->de_FileSize), pmp->pm_bpcluster, + NOCRED, &bp); + if (error != 0) + goto rewind; + vfs_bio_clrbuf(bp); + if (!DOINGASYNC(vp)) + (void)bwrite(bp); + else if (vm_page_count_severe() || buf_dirty_count_severe()) + bawrite(bp); + else + bdwrite(bp); + vnode_pager_setsize(vp, length); dep->de_FileSize = length; dep->de_flag |= DE_UPDATE | DE_MODIFIED; return (deupdat(dep, !DOINGASYNC(vp))); + +rewind: + /* truncate the added clusters away again */ + (void)detrunc(dep, dep->de_FileSize, 0, cred); + return (error); } /*
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