diff mbox series

loop: don't print warnings if the underlying filesystem doesn't support discard

Message ID alpine.LRH.2.02.2109231539520.27863@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive)
State New, archived
Headers show
Series loop: don't print warnings if the underlying filesystem doesn't support discard | expand

Commit Message

Mikulas Patocka Sept. 23, 2021, 7:48 p.m. UTC 
Hi

When running the lvm testsuite, we get a lot of warnings 
"blk_update_request: operation not supported error, dev loop0, sector 0 op 
0x9:(WRITE_ZEROES) flags 0x800800 phys_seg 0 prio class 0". The lvm 
testsuite puts the loop device on tmpfs and the reason for the warning is 
that tmpfs supports fallocate, but doesn't support FALLOC_FL_ZERO_RANGE.

I've created this patch to silence the warnings.

Mikulas



From: Mikulas Patocka <mpatocka@redhat.com>

The loop driver checks for the fallocate method and if it is present, it
assumes that the filesystem can do FALLOC_FL_ZERO_RANGE and
FALLOC_FL_PUNCH_HOLE requests. However, some filesystems (such as fat, or
tmpfs) have the fallocate method, but lack the capability to do
FALLOC_FL_ZERO_RANGE and/or FALLOC_FL_PUNCH_HOLE.

This results in syslog warnings "blk_update_request: operation not
supported error, dev loop0, sector 0 op 0x9:(WRITE_ZEROES) flags 0x800800
phys_seg 0 prio class 0"

This patch sets RQF_QUIET to silence the warnings.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org

---
 drivers/block/loop.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

Ming Lei Sept. 24, 2021, 12:17 a.m. UTC | #1 
On Thu, Sep 23, 2021 at 03:48:27PM -0400, Mikulas Patocka wrote:
> Hi
> 
> When running the lvm testsuite, we get a lot of warnings 
> "blk_update_request: operation not supported error, dev loop0, sector 0 op 
> 0x9:(WRITE_ZEROES) flags 0x800800 phys_seg 0 prio class 0". The lvm 
> testsuite puts the loop device on tmpfs and the reason for the warning is 
> that tmpfs supports fallocate, but doesn't support FALLOC_FL_ZERO_RANGE.
> 
> I've created this patch to silence the warnings.
> 
> Mikulas
> 
> 
> 
> From: Mikulas Patocka <mpatocka@redhat.com>
> 
> The loop driver checks for the fallocate method and if it is present, it
> assumes that the filesystem can do FALLOC_FL_ZERO_RANGE and
> FALLOC_FL_PUNCH_HOLE requests. However, some filesystems (such as fat, or
> tmpfs) have the fallocate method, but lack the capability to do
> FALLOC_FL_ZERO_RANGE and/or FALLOC_FL_PUNCH_HOLE.
> 
> This results in syslog warnings "blk_update_request: operation not
> supported error, dev loop0, sector 0 op 0x9:(WRITE_ZEROES) flags 0x800800
> phys_seg 0 prio class 0"
> 
> This patch sets RQF_QUIET to silence the warnings.
> 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Cc: stable@vger.kernel.org
> 
> ---
>  drivers/block/loop.c |   11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/drivers/block/loop.c
> ===================================================================
> --- linux-2.6.orig/drivers/block/loop.c	2021-09-23 17:06:57.000000000 +0200
> +++ linux-2.6/drivers/block/loop.c	2021-09-23 21:29:39.000000000 +0200
> @@ -493,7 +493,16 @@ static int lo_fallocate(struct loop_devi
>  	ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
>  	if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
>  		ret = -EIO;
> - out:
> +out:
> +
> +	/*
> +	 * Some filesystems have the fallocate method, but lack the capability
> +	 * to do FALLOC_FL_ZERO_RANGE and/or FALLOC_FL_PUNCH_HOLE requests.
> +	 * We do not want a syslog warning in this case.
> +	 */
> +	if (ret == -EOPNOTSUPP)
> +		rq->rq_flags |= RQF_QUIET;
> +

Looks fine,

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Christoph Hellwig Sept. 24, 2021, 3:58 p.m. UTC | #2 
On Thu, Sep 23, 2021 at 03:48:27PM -0400, Mikulas Patocka wrote:
> Hi
> 
> When running the lvm testsuite, we get a lot of warnings 
> "blk_update_request: operation not supported error, dev loop0, sector 0 op 
> 0x9:(WRITE_ZEROES) flags 0x800800 phys_seg 0 prio class 0". The lvm 
> testsuite puts the loop device on tmpfs and the reason for the warning is 
> that tmpfs supports fallocate, but doesn't support FALLOC_FL_ZERO_RANGE.
> 
> I've created this patch to silence the warnings.
> 
> Mikulas
> 
> 
> 
> From: Mikulas Patocka <mpatocka@redhat.com>
> 
> The loop driver checks for the fallocate method and if it is present, it
> assumes that the filesystem can do FALLOC_FL_ZERO_RANGE and
> FALLOC_FL_PUNCH_HOLE requests. However, some filesystems (such as fat, or
> tmpfs) have the fallocate method, but lack the capability to do
> FALLOC_FL_ZERO_RANGE and/or FALLOC_FL_PUNCH_HOLE.
> 
> This results in syslog warnings "blk_update_request: operation not
> supported error, dev loop0, sector 0 op 0x9:(WRITE_ZEROES) flags 0x800800
> phys_seg 0 prio class 0"
> 
> This patch sets RQF_QUIET to silence the warnings.

Doesn't this just paper over the problem?  I think we need an
unsigned int with flag in the file_operations for the supported
operations for this kind of use.
Mikulas Patocka Oct. 4, 2021, 1:01 p.m. UTC | #3 
On Fri, 24 Sep 2021, Christoph Hellwig wrote:

> On Thu, Sep 23, 2021 at 03:48:27PM -0400, Mikulas Patocka wrote:
> > Hi
> > 
> > When running the lvm testsuite, we get a lot of warnings 
> > "blk_update_request: operation not supported error, dev loop0, sector 0 op 
> > 0x9:(WRITE_ZEROES) flags 0x800800 phys_seg 0 prio class 0". The lvm 
> > testsuite puts the loop device on tmpfs and the reason for the warning is 
> > that tmpfs supports fallocate, but doesn't support FALLOC_FL_ZERO_RANGE.
> > 
> > I've created this patch to silence the warnings.
> > 
> > Mikulas
> > 
> > 
> > 
> > From: Mikulas Patocka <mpatocka@redhat.com>
> > 
> > The loop driver checks for the fallocate method and if it is present, it
> > assumes that the filesystem can do FALLOC_FL_ZERO_RANGE and
> > FALLOC_FL_PUNCH_HOLE requests. However, some filesystems (such as fat, or
> > tmpfs) have the fallocate method, but lack the capability to do
> > FALLOC_FL_ZERO_RANGE and/or FALLOC_FL_PUNCH_HOLE.
> > 
> > This results in syslog warnings "blk_update_request: operation not
> > supported error, dev loop0, sector 0 op 0x9:(WRITE_ZEROES) flags 0x800800
> > phys_seg 0 prio class 0"
> > 
> > This patch sets RQF_QUIET to silence the warnings.
> 
> Doesn't this just paper over the problem?  I think we need an
> unsigned int with flag in the file_operations for the supported
> operations for this kind of use.

Do you want this patch?

Mikulas



From: Mikulas Patocka <mpatocka@redhat.com>

The loop driver checks for the fallocate method and if it is present, it 
assumes that the filesystem can do FALLOC_FL_ZERO_RANGE and 
FALLOC_FL_PUNCH_HOLE requests. However, some filesystems (such as fat, or 
tmpfs) have the fallocate method, but lack the capability to do 
FALLOC_FL_ZERO_RANGE and/or FALLOC_FL_PUNCH_HOLE.

This results in syslog warnings "blk_update_request: operation not 
supported error, dev loop0, sector 0 op 0x9:(WRITE_ZEROES) flags 0x800800 
phys_seg 0 prio class 0". The error can be reproduced with this command:
"truncate -s 1GiB /tmp/file; losetup /dev/loop0 /tmp/file; blkdiscard -z /dev/loop0"

This patch introduces a field "fallocate_flags" in struct file_operations 
that specifies the flags that are supported by the fallocate methods. The 
loopback driver will check this field to determine if FALLOC_FL_PUNCH_HOLE 
or FALLOC_FL_ZERO_RANGE is supported

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Index: linux-2.6/block/fops.c
===================================================================
--- linux-2.6.orig/block/fops.c
+++ linux-2.6/block/fops.c
@@ -628,6 +628,7 @@ const struct file_operations def_blk_fop
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= blkdev_fallocate,
+	.fallocate_flags = BLKDEV_FALLOC_FL_SUPPORTED,
 };
 
 static __init int blkdev_init(void)
Index: linux-2.6/fs/btrfs/file.c
===================================================================
--- linux-2.6.orig/fs/btrfs/file.c
+++ linux-2.6/fs/btrfs/file.c
@@ -3688,6 +3688,7 @@ const struct file_operations btrfs_file_
 	.release	= btrfs_release_file,
 	.fsync		= btrfs_sync_file,
 	.fallocate	= btrfs_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE,
 	.unlocked_ioctl	= btrfs_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= btrfs_compat_ioctl,
Index: linux-2.6/fs/ceph/file.c
===================================================================
--- linux-2.6.orig/fs/ceph/file.c
+++ linux-2.6/fs/ceph/file.c
@@ -2492,5 +2492,6 @@ const struct file_operations ceph_file_f
 	.unlocked_ioctl = ceph_ioctl,
 	.compat_ioctl = compat_ptr_ioctl,
 	.fallocate	= ceph_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
 	.copy_file_range = ceph_copy_file_range,
 };
Index: linux-2.6/fs/cifs/cifsfs.c
===================================================================
--- linux-2.6.orig/fs/cifs/cifsfs.c
+++ linux-2.6/fs/cifs/cifsfs.c
@@ -1281,6 +1281,7 @@ const struct file_operations cifs_file_o
 	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE,
 };
 
 const struct file_operations cifs_file_strict_ops = {
@@ -1301,6 +1302,7 @@ const struct file_operations cifs_file_s
 	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE,
 };
 
 const struct file_operations cifs_file_direct_ops = {
@@ -1321,6 +1323,7 @@ const struct file_operations cifs_file_d
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE,
 };
 
 const struct file_operations cifs_file_nobrl_ops = {
@@ -1339,6 +1342,7 @@ const struct file_operations cifs_file_n
 	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE,
 };
 
 const struct file_operations cifs_file_strict_nobrl_ops = {
@@ -1357,6 +1361,7 @@ const struct file_operations cifs_file_s
 	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE,
 };
 
 const struct file_operations cifs_file_direct_nobrl_ops = {
@@ -1375,6 +1380,7 @@ const struct file_operations cifs_file_d
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE,
 };
 
 const struct file_operations cifs_dir_ops = {
Index: linux-2.6/fs/ext4/file.c
===================================================================
--- linux-2.6.orig/fs/ext4/file.c
+++ linux-2.6/fs/ext4/file.c
@@ -929,6 +929,7 @@ const struct file_operations ext4_file_o
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ext4_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_INSERT_RANGE,
 };
 
 const struct inode_operations ext4_file_inode_operations = {
Index: linux-2.6/fs/f2fs/file.c
===================================================================
--- linux-2.6.orig/fs/f2fs/file.c
+++ linux-2.6/fs/f2fs/file.c
@@ -4499,6 +4499,7 @@ const struct file_operations f2fs_file_o
 	.flush		= f2fs_file_flush,
 	.fsync		= f2fs_sync_file,
 	.fallocate	= f2fs_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_INSERT_RANGE,
 	.unlocked_ioctl	= f2fs_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= f2fs_compat_ioctl,
Index: linux-2.6/fs/fat/file.c
===================================================================
--- linux-2.6.orig/fs/fat/file.c
+++ linux-2.6/fs/fat/file.c
@@ -211,6 +211,7 @@ const struct file_operations fat_file_op
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= fat_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE,
 };
 
 static int fat_cont_expand(struct inode *inode, loff_t size)
Index: linux-2.6/fs/fuse/file.c
===================================================================
--- linux-2.6.orig/fs/fuse/file.c
+++ linux-2.6/fs/fuse/file.c
@@ -3147,6 +3147,7 @@ static const struct file_operations fuse
 	.compat_ioctl	= fuse_file_compat_ioctl,
 	.poll		= fuse_file_poll,
 	.fallocate	= fuse_file_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE,
 	.copy_file_range = fuse_copy_file_range,
 };
 
Index: linux-2.6/fs/gfs2/file.c
===================================================================
--- linux-2.6.orig/fs/gfs2/file.c
+++ linux-2.6/fs/gfs2/file.c
@@ -1366,6 +1366,7 @@ const struct file_operations gfs2_file_f
 	.splice_write	= gfs2_file_splice_write,
 	.setlease	= simple_nosetlease,
 	.fallocate	= gfs2_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 };
 
 const struct file_operations gfs2_dir_fops = {
Index: linux-2.6/fs/hugetlbfs/inode.c
===================================================================
--- linux-2.6.orig/fs/hugetlbfs/inode.c
+++ linux-2.6/fs/hugetlbfs/inode.c
@@ -1163,6 +1163,7 @@ const struct file_operations hugetlbfs_f
 	.get_unmapped_area	= hugetlb_get_unmapped_area,
 	.llseek			= default_llseek,
 	.fallocate		= hugetlbfs_fallocate,
+	.fallocate_flags	= FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
 };
 
 static const struct inode_operations hugetlbfs_dir_inode_operations = {
Index: linux-2.6/fs/nfs/nfs4file.c
===================================================================
--- linux-2.6.orig/fs/nfs/nfs4file.c
+++ linux-2.6/fs/nfs/nfs4file.c
@@ -457,6 +457,7 @@ const struct file_operations nfs4_file_o
 	.copy_file_range = nfs4_copy_file_range,
 	.llseek		= nfs4_file_llseek,
 	.fallocate	= nfs42_fallocate,
+	.fallocate_flags = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 	.remap_file_range = nfs42_remap_file_range,
 #else
 	.llseek		= nfs_file_llseek,
Index: linux-2.6/fs/ntfs3/file.c
===================================================================
--- linux-2.6.orig/fs/ntfs3/file.c
+++ linux-2.6/fs/ntfs3/file.c
@@ -1246,6 +1246,7 @@ const struct file_operations ntfs_file_o
 	.fsync		= generic_file_fsync,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ntfs_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE,
 	.release	= ntfs_file_release,
 };
 // clang-format on
Index: linux-2.6/fs/ocfs2/file.c
===================================================================
--- linux-2.6.orig/fs/ocfs2/file.c
+++ linux-2.6/fs/ocfs2/file.c
@@ -2746,6 +2746,7 @@ const struct file_operations ocfs2_fops
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ocfs2_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
 	.remap_file_range = ocfs2_remap_file_range,
 };
 
@@ -2792,6 +2793,7 @@ const struct file_operations ocfs2_fops_
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ocfs2_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
 	.remap_file_range = ocfs2_remap_file_range,
 };
 
Index: linux-2.6/fs/overlayfs/file.c
===================================================================
--- linux-2.6.orig/fs/overlayfs/file.c
+++ linux-2.6/fs/overlayfs/file.c
@@ -645,6 +645,7 @@ const struct file_operations ovl_file_op
 	.fsync		= ovl_fsync,
 	.mmap		= ovl_mmap,
 	.fallocate	= ovl_fallocate,
+	.fallocate_flags = FALLOC_FL_SUPPORTED_MASK,
 	.fadvise	= ovl_fadvise,
 	.flush		= ovl_flush,
 	.splice_read    = generic_file_splice_read,
Index: linux-2.6/fs/xfs/xfs_file.c
===================================================================
--- linux-2.6.orig/fs/xfs/xfs_file.c
+++ linux-2.6/fs/xfs/xfs_file.c
@@ -1464,6 +1464,7 @@ const struct file_operations xfs_file_op
 	.fsync		= xfs_file_fsync,
 	.get_unmapped_area = thp_get_unmapped_area,
 	.fallocate	= xfs_file_fallocate,
+	.fallocate_flags = XFS_FALLOC_FL_SUPPORTED,
 	.fadvise	= xfs_file_fadvise,
 	.remap_file_range = xfs_file_remap_range,
 };
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -2098,6 +2098,7 @@ struct file_operations {
 	int (*setlease)(struct file *, long, struct file_lock **, void **);
 	long (*fallocate)(struct file *file, int mode, loff_t offset,
 			  loff_t len);
+	unsigned fallocate_flags;
 	void (*show_fdinfo)(struct seq_file *m, struct file *f);
 #ifndef CONFIG_MMU
 	unsigned (*mmap_capabilities)(struct file *);
Index: linux-2.6/ipc/shm.c
===================================================================
--- linux-2.6.orig/ipc/shm.c
+++ linux-2.6/ipc/shm.c
@@ -44,6 +44,7 @@
 #include <linux/mount.h>
 #include <linux/ipc_namespace.h>
 #include <linux/rhashtable.h>
+#include <linux/falloc.h>
 
 #include <linux/uaccess.h>
 
@@ -558,6 +559,7 @@ static const struct file_operations shm_
 	.get_unmapped_area	= shm_get_unmapped_area,
 	.llseek		= noop_llseek,
 	.fallocate	= shm_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
 };
 
 /*
@@ -571,6 +573,7 @@ static const struct file_operations shm_
 	.get_unmapped_area	= shm_get_unmapped_area,
 	.llseek		= noop_llseek,
 	.fallocate	= shm_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
 };
 
 bool is_file_shm_hugepages(struct file *file)
Index: linux-2.6/mm/shmem.c
===================================================================
--- linux-2.6.orig/mm/shmem.c
+++ linux-2.6/mm/shmem.c
@@ -3797,6 +3797,7 @@ static const struct file_operations shme
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= shmem_fallocate,
+	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
 #endif
 };
 
Index: linux-2.6/drivers/block/loop.c
===================================================================
--- linux-2.6.orig/drivers/block/loop.c
+++ linux-2.6/drivers/block/loop.c
@@ -947,7 +947,9 @@ static void loop_config_discard(struct l
 	 * encryption is enabled, because it may give an attacker
 	 * useful information.
 	 */
-	} else if (!file->f_op->fallocate || lo->lo_encrypt_key_size) {
+	} else if ((file->f_op->fallocate_flags & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE)) !=
+						  (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE) ||
+		   lo->lo_encrypt_key_size) {
 		max_discard_sectors = 0;
 		granularity = 0;
 
@@ -959,7 +961,10 @@ static void loop_config_discard(struct l
 	if (max_discard_sectors) {
 		q->limits.discard_granularity = granularity;
 		blk_queue_max_discard_sectors(q, max_discard_sectors);
-		blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
+		if (file->f_op->fallocate_flags & FALLOC_FL_ZERO_RANGE)
+			blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
+		else
+			blk_queue_max_write_zeroes_sectors(q, 0);
 		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 	} else {
 		q->limits.discard_granularity = 0;
Christoph Hellwig Oct. 12, 2021, 6:20 a.m. UTC | #4 
On Mon, Oct 04, 2021 at 09:01:33AM -0400, Mikulas Patocka wrote:
> Do you want this patch?

Yes, this looks like what I want.  Minor nitpicks below:

> +	.fallocate_flags = BLKDEV_FALLOC_FL_SUPPORTED,

I'd probably call this fallocate_supported_flags.

> +	.fallocate_flags = FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE,

Please avoid over 80 lines for a plain list of flags.
diff mbox series

Patch

Index: linux-2.6/drivers/block/loop.c
===================================================================
--- linux-2.6.orig/drivers/block/loop.c	2021-09-23 17:06:57.000000000 +0200
+++ linux-2.6/drivers/block/loop.c	2021-09-23 21:29:39.000000000 +0200
@@ -493,7 +493,16 @@  static int lo_fallocate(struct loop_devi
 	ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
 	if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
 		ret = -EIO;
- out:
+out:
+
+	/*
+	 * Some filesystems have the fallocate method, but lack the capability
+	 * to do FALLOC_FL_ZERO_RANGE and/or FALLOC_FL_PUNCH_HOLE requests.
+	 * We do not want a syslog warning in this case.
+	 */
+	if (ret == -EOPNOTSUPP)
+		rq->rq_flags |= RQF_QUIET;
+
 	return ret;
 }