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X-MS-Exchange-CrossTenant-Network-Message-Id: 4789e266-83c6-4dac-1237-08ddd6a53e4e X-MS-Exchange-CrossTenant-AuthSource: BN0PR10MB5128.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Aug 2025 17:58:56.0778 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: +MGGX7mptsvk3drNVaVIqSukhEQU1IN/LYSEyriQMaWgyhTyB2oe+ItPMolpWAvhGywN2ZZ2wx3ED/zh236krg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ5PPFA634C6E92 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-08_05,2025-08-06_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxscore=0 adultscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 bulkscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2507300000 definitions=main-2508080146 X-Authority-Analysis: v=2.4 cv=WMp/XmsR c=1 sm=1 tr=0 ts=68963ae3 cx=c_pps a=XiAAW1AwiKB2Y8Wsi+sD2Q==:117 a=XiAAW1AwiKB2Y8Wsi+sD2Q==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=z/mQ4Ysz8XfWz/Q5cLBRGdckG28=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=wKuvFiaSGQ0qltdbU6+NXLB8nM8=:19 a=Ol13hO9ccFRV9qXi2t6ftBPywas=:19 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=GoEa3M9JfhUA:10 a=VwQbUJbxAAAA:8 a=3_-2tfhjUFWtIkyxEnoA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: 4mEygF8GI7mKy3E9Y_ax2M7jlBBn7Eng X-Proofpoint-ORIG-GUID: 4mEygF8GI7mKy3E9Y_ax2M7jlBBn7Eng X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA4MDE0NiBTYWx0ZWRfXzEdLKo6C76kX P1VhOcBTSO6T0OXbwGU1f5yVQhNBr6f41FVStEqSODEkURdjyvs3QE1OxXkvnMQMdFmRX5ZOK8t g8uTYBQEJuXJoYpy8Vcrs9AFHlaJ29BVLfAiIe06AA5OhYAPQAl7dTblc7uREhBe4GX0xPFKk3A zgvKdv/5mnZspWwm/A71K8bkyGbKCOxWaYoID61QrMGG/vV6Dj9mjmffwVkWsM83HYODtuPJfXy Z495N1O2Tiqs/1I6vlURKZrdou5OIzvGCgxa2BcYo2jjIkHnrIki/f9GO8WNXKjfaSujMcETKcC pEM3Rvz/YbeTtE35gGDTzMHRj3jmcrueIpR0Ei/tXgJNoT9t9Vpo5FPVjaO2WOdVoWrXzSM7n88 JVeoX225uYTNbte4A3vVT63mzBlZy3sSbLQV10T7F59jPxXAfiKXkX0A5HWRcDmGG2LNa6kN On 8/7/25 12:25 PM, Mike Snitzer wrote: > Add 'io_cache_write' to NFSD's debugfs interface so that: Any data > written by NFSD will either be: > - cached using page cache (NFSD_IO_BUFFERED=1) > - cached but removed from the page cache upon completion > (NFSD_IO_DONTCACHE=2). > - not cached (NFSD_IO_DIRECT=3) > > io_cache_write may be set by writing to: > /sys/kernel/debug/nfsd/io_cache_write > > If NFSD_IO_DONTCACHE is specified using 2, FOP_DONTCACHE must be > advertised as supported by the underlying filesystem (e.g. XFS), > otherwise all IO flagged with RWF_DONTCACHE will fail with > -EOPNOTSUPP. > > If NFSD_IO_DIRECT is specified using 3, the IO must be aligned > relative to the underlying block device's logical_block_size. Also the > memory buffer used to store the WRITE payload must be aligned relative > to the underlying block device's dma_alignment. > > Signed-off-by: Mike Snitzer > --- > fs/nfsd/debugfs.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ > fs/nfsd/nfsd.h | 1 + > fs/nfsd/vfs.c | 16 ++++++++++++++++ > 3 files changed, 61 insertions(+) > > diff --git a/fs/nfsd/debugfs.c b/fs/nfsd/debugfs.c > index c07f71d4e84f4..872de65f0e9ac 100644 > --- a/fs/nfsd/debugfs.c > +++ b/fs/nfsd/debugfs.c > @@ -87,6 +87,47 @@ static int nfsd_io_cache_read_set(void *data, u64 val) > DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_read_fops, nfsd_io_cache_read_get, > nfsd_io_cache_read_set, "%llu\n"); > > +/* > + * /sys/kernel/debug/nfsd/io_cache_write > + * > + * Contents: > + * %1: NFS WRITE will use buffered IO > + * %2: NFS WRITE will use dontcache (buffered IO w/ dropbehind) > + * %3: NFS WRITE will use direct IO > + * > + * The default value of this setting is zero (UNSPECIFIED). > + * This setting takes immediate effect for all NFS versions, > + * all exports, and in all NFSD net namespaces. > + */ > + > +static int nfsd_io_cache_write_get(void *data, u64 *val) > +{ > + *val = nfsd_io_cache_write; > + return 0; > +} > + > +static int nfsd_io_cache_write_set(void *data, u64 val) > +{ > + int ret = 0; > + > + switch (val) { > + case NFSD_IO_BUFFERED: > + case NFSD_IO_DONTCACHE: > + case NFSD_IO_DIRECT: > + nfsd_io_cache_write = val; > + break; > + default: > + nfsd_io_cache_write = NFSD_IO_UNSPECIFIED; > + ret = -EINVAL; I might be wrong, but an error return should leave the setting untouched, IMO. Likewise for the read setting. > + break; > + } > + > + return ret; > +} > + > +DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_write_fops, nfsd_io_cache_write_get, > + nfsd_io_cache_write_set, "%llu\n"); > + > void nfsd_debugfs_exit(void) > { > debugfs_remove_recursive(nfsd_top_dir); > @@ -102,4 +143,7 @@ void nfsd_debugfs_init(void) > > debugfs_create_file("io_cache_read", S_IWUSR | S_IRUGO, > nfsd_top_dir, NULL, &nfsd_io_cache_read_fops); > + > + debugfs_create_file("io_cache_write", S_IWUSR | S_IRUGO, > + nfsd_top_dir, NULL, &nfsd_io_cache_write_fops); > } > diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h > index 6ef799405145f..fe935b4cda538 100644 > --- a/fs/nfsd/nfsd.h > +++ b/fs/nfsd/nfsd.h > @@ -161,6 +161,7 @@ enum { > }; > > extern u64 nfsd_io_cache_read __read_mostly; > +extern u64 nfsd_io_cache_write __read_mostly; > > extern int nfsd_max_blksize; > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 26b6d96258711..5768244c7a3c3 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -50,6 +50,7 @@ > > bool nfsd_disable_splice_read __read_mostly; > u64 nfsd_io_cache_read __read_mostly; > +u64 nfsd_io_cache_write __read_mostly; > > /** > * nfserrno - Map Linux errnos to NFS errnos > @@ -1234,6 +1235,21 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, > > nvecs = xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, payload); > iov_iter_bvec(&iter, ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt); > + > + switch (nfsd_io_cache_write) { > + case NFSD_IO_DIRECT: > + /* direct I/O must be aligned to device logical sector size */ > + if (nf->nf_dio_mem_align && nf->nf_dio_offset_align && > + (((offset | *cnt) & (nf->nf_dio_offset_align-1)) == 0)) > + kiocb.ki_flags |= IOCB_DIRECT; > + break; > + case NFSD_IO_DONTCACHE: > + kiocb.ki_flags |= IOCB_DONTCACHE; > + break; > + case NFSD_IO_BUFFERED: > + break; > + } > + > since = READ_ONCE(file->f_wb_err); > if (verf) > nfsd_copy_write_verifier(verf, nn); -- Chuck Lever