kernel/linux.git/fs/9p, branch v5.10.268

9p: skip nlink update in cacheless mode to fix WARN_ON

2026-08-23T12:16:20+00:00

[ Upstream commit 574aa0b4799470ac814479f1138d19efe6262255 ] v9fs_dec_count() unconditionally calls drop_nlink() on regular files, even when the inode's nlink is already zero. In cacheless mode the client refetches inode metadata from the server (the source of truth) on every operation, so by the time v9fs_remove() returns, the locally cached nlink may already reflect the post-unlink value: 1. Client initiates unlink, server processes it and sets nlink to 0 2. Client refetches inode metadata (nlink=0) before unlink returns 3. Client's v9fs_remove() completes successfully 4. Client calls v9fs_dec_count() which calls drop_nlink() on nlink=0 This race is easily triggered under heavy unlink workloads, such as stress-ng's unlink stressor, producing the following warning: WARNING: fs/inode.c:417 at drop_nlink+0x4c/0xc8 Call trace: drop_nlink+0x4c/0xc8 v9fs_remove+0x1e0/0x250 [9p] v9fs_vfs_unlink+0x20/0x38 [9p] vfs_unlink+0x13c/0x258 ... In cacheless mode the server is authoritative and the inode is on its way out, so locally adjusting nlink buys nothing. Skip v9fs_dec_count() entirely when neither CACHE_META nor CACHE_LOOSE is set, which both avoids the warning and removes a class of nlink races (two concurrent unlinkers observing nlink > 0 and both calling drop_nlink()) that an nlink == 0 guard alone would only narrow rather than close. Fixes: ac89b2ef9b55 ("9p: don't maintain dir i_nlink if the exported fs doesn't either") Cc: stable@vger.kernel.org Suggested-by: Dominique Martinet Signed-off-by: Breno Leitao Message-ID: <20260421-9p-v2-1-48762d294fad@debian.org> Signed-off-by: Dominique Martinet [ Adapted `v9ses->cache & (CACHE_META | CACHE_LOOSE)` bitmask test to the pre-bitmask exclusive enum form `v9ses->cache != CACHE_LOOSE && v9ses->cache != CACHE_FSCACHE`. ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

use less confusing names for iov_iter direction initializers

2026-06-19T11:21:45+00:00

[ Upstream commit de4eda9de2d957ef2d6a8365a01e26a435e958cb ] READ/WRITE proved to be actively confusing - the meanings are "data destination, as used with read(2)" and "data source, as used with write(2)", but people keep interpreting those as "we read data from it" and "we write data to it", i.e. exactly the wrong way. Call them ITER_DEST and ITER_SOURCE - at least that is harder to misinterpret... Signed-off-by: Al Viro Stable-dep-of: a4f0b001782b ("vsock/virtio: reset connection on receiving queue overflow") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

9p: sysfs_init: don't hardcode error to ENOMEM

2025-12-06T21:08:15+00:00

[ Upstream commit 528f218b31aac4bbfc58914d43766a22ab545d48 ] v9fs_sysfs_init() always returned -ENOMEM on failure; return the actual sysfs_create_group() error instead. Signed-off-by: Randall P. Embry Message-ID: <20250926-v9fs_misc-v1-3-a8b3907fc04d@codewreck.org> Signed-off-by: Dominique Martinet Signed-off-by: Sasha Levin

9p: fix /sys/fs/9p/caches overwriting itself

2025-12-06T21:08:15+00:00

[ Upstream commit 86db0c32f16c5538ddb740f54669ace8f3a1f3d7 ] caches_show() overwrote its buffer on each iteration, so only the last cache tag was visible in sysfs output. Properly append with snprintf(buf + count, …). Signed-off-by: Randall P. Embry Message-ID: <20250926-v9fs_misc-v1-2-a8b3907fc04d@codewreck.org> Signed-off-by: Dominique Martinet Signed-off-by: Sasha Levin

fs/9p: drop inodes immediately on non-.L too

2024-05-17T09:48:05+00:00

[ Upstream commit 7fd524b9bd1be210fe79035800f4bd78a41b349f ] Signed-off-by: Joakim Sindholt Signed-off-by: Eric Van Hensbergen Signed-off-by: Sasha Levin

9p: explicitly deny setlease attempts

2024-05-17T09:48:05+00:00

[ Upstream commit 7a84602297d36617dbdadeba55a2567031e5165b ] 9p is a remote network protocol, and it doesn't support asynchronous notifications from the server. Ensure that we don't hand out any leases since we can't guarantee they'll be broken when a file's contents change. Signed-off-by: Jeff Layton Signed-off-by: Eric Van Hensbergen Signed-off-by: Sasha Levin

fs/9p: translate O_TRUNC into OTRUNC

2024-05-17T09:48:05+00:00

[ Upstream commit 87de39e70503e04ddb58965520b15eb9efa7eef3 ] This one hits both 9P2000 and .u as it appears v9fs has never translated the O_TRUNC flag. Signed-off-by: Joakim Sindholt Signed-off-by: Eric Van Hensbergen Signed-off-by: Sasha Levin

fs/9p: only translate RWX permissions for plain 9P2000

2024-05-17T09:48:05+00:00

[ Upstream commit cd25e15e57e68a6b18dc9323047fe9c68b99290b ] Garbage in plain 9P2000's perm bits is allowed through, which causes it to be able to set (among others) the suid bit. This was presumably not the intent since the unix extended bits are handled explicitly and conditionally on .u. Signed-off-by: Joakim Sindholt Signed-off-by: Eric Van Hensbergen Signed-off-by: Sasha Levin

9p: missing chunk of "fs/9p: Don't update file type when updating file attributes"

2022-06-22T12:13:12+00:00

commit b577d0cd2104fdfcf0ded3707540a12be8ddd8b0 upstream. In commit 45089142b149 Aneesh had missed one (admittedly, very unlikely to hit) case in v9fs_stat2inode_dotl(). However, the same considerations apply there as well - we have no business whatsoever to change ->i_rdev or the file type. Cc: Tadeusz Struk Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

9p: only copy valid iattrs in 9P2000.L setattr implementation

2022-01-20T08:17:50+00:00

commit 3cb6ee991496b67ee284c6895a0ba007e2d7bac3 upstream. The 9P2000.L setattr method v9fs_vfs_setattr_dotl() copies struct iattr values without checking whether they are valid causing unitialized values to be copied. The 9P2000 setattr method v9fs_vfs_setattr() method gets this right. Check whether struct iattr fields are valid first before copying in v9fs_vfs_setattr_dotl() too and make sure that all other fields are set to 0 apart from {g,u}id which should be set to INVALID_{G,U}ID. This ensure that they can be safely sent over the wire or printed for debugging later on. Link: https://lkml.kernel.org/r/20211129114434.3637938-1-brauner@kernel.org Link: https://lkml.kernel.org/r/000000000000a0d53f05d1c72a4c%40google.com Cc: Eric Van Hensbergen Cc: Latchesar Ionkov Cc: Dominique Martinet Cc: stable@kernel.org Cc: v9fs-developer@lists.sourceforge.net Reported-by: syzbot+dfac92a50024b54acaa4@syzkaller.appspotmail.com Signed-off-by: Christian Brauner [Dominique: do not set a/mtime with just ATTR_A/MTIME as discussed] Signed-off-by: Dominique Martinet Signed-off-by: Greg Kroah-Hartman