| Message ID | 20240813073527.81072-3-hch@lst.de (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | [1/5] statx.h: update to latest kernel UAPI | expand |
On Tue, Aug 13, 2024 at 09:35:01AM +0200, Christoph Hellwig wrote: > Add a new C program to find the minimum direct I/O alignment. This > uses the statx stx_dio_offset_align field if provided, then falls > back to the BLKSSZGET ioctl for block backed file systems and finally > the page size. It is intended as a more capable replacement for the > _min_dio_alignment bash helper. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > src/Makefile | 2 +- > src/min_dio_alignment.c | 66 +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 67 insertions(+), 1 deletion(-) > create mode 100644 src/min_dio_alignment.c > > diff --git a/src/Makefile b/src/Makefile > index 559209be9..b3da59a0e 100644 > --- a/src/Makefile > +++ b/src/Makefile > @@ -34,7 +34,7 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ > attr_replace_test swapon mkswap t_attr_corruption t_open_tmpfiles \ > fscrypt-crypt-util bulkstat_null_ocount splice-test chprojid_fail \ > detached_mounts_propagation ext4_resize t_readdir_3 splice2pipe \ > - uuid_ioctl t_snapshot_deleted_subvolume fiemap-fault > + uuid_ioctl t_snapshot_deleted_subvolume fiemap-fault min_dio_alignment > > EXTRA_EXECS = dmerror fill2attr fill2fs fill2fs_check scaleread.sh \ > btrfs_crc32c_forged_name.py popdir.pl popattr.py \ > diff --git a/src/min_dio_alignment.c b/src/min_dio_alignment.c > new file mode 100644 > index 000000000..c3345bfb2 > --- /dev/null > +++ b/src/min_dio_alignment.c > @@ -0,0 +1,66 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2024 Christoph Hellwig > + */ > +#include <fcntl.h> > +#include <stdio.h> > +#include <stdlib.h> > +#include <unistd.h> > +#include <sys/mount.h> > +#include <sys/ioctl.h> > +#include <sys/stat.h> > +#include "statx.h" > + > +static int min_dio_alignmenent(const char *mntpnt, const char *devname) min_dio_alignment > +{ > + struct statx stx = { }; > + struct stat st; > + int fd; > + > + /* > + * If the file system supports STATX_DIOALIGN, use the dio_offset_align > + * member, as that reports exactly the information that we are asking > + * for. > + * > + * STATX_DIOALIGN is only reported on regular files, so use O_TMPFILE > + * to create one without leaving a trace. > + */ > + fd = open(mntpnt, O_TMPFILE | O_RDWR | O_EXCL, 0600); > + if (fd >= 0 && > + xfstests_statx(fd, "", AT_EMPTY_PATH, STATX_DIOALIGN, &stx) == 0 && > + (stx.stx_mask & STATX_DIOALIGN)) > + return stx.stx_dio_offset_align; > + > + /* > + * If we are on a block device and no explicit aligned is reported, use > + * the logical block size as a guestimate. > + */ > + if (stat(devname, &st) == 0 && S_ISBLK(st.st_mode)) { > + int dev_fd = open(devname, O_RDONLY); > + int logical_block_size; > + > + if (dev_fd > 0 && > + fstat(dev_fd, &st) == 0 && > + S_ISBLK(st.st_mode) && > + ioctl(dev_fd, BLKSSZGET, &logical_block_size)) { > + return logical_block_size; > + } > + } > + > + /* > + * No support for STATX_DIOALIGN and not a block device: > + * default to PAGE_SIZE. Should we try DIOINFO here as a second to last gasp? --D > + */ > + return getpagesize(); > +} > + > +int main(int argc, char **argv) > +{ > + if (argc != 3) { > + fprintf(stderr, "usage: %s mountpoint devicename\n", argv[0]); > + exit(1); > + } > + > + printf("%d\n", min_dio_alignmenent(argv[1], argv[2])); > + exit(0); > +} > -- > 2.43.0 > >
On Tue, Aug 13, 2024 at 07:40:04AM -0700, Darrick J. Wong wrote: > On Tue, Aug 13, 2024 at 09:35:01AM +0200, Christoph Hellwig wrote: > > Add a new C program to find the minimum direct I/O alignment. This > > uses the statx stx_dio_offset_align field if provided, then falls > > back to the BLKSSZGET ioctl for block backed file systems and finally > > the page size. It is intended as a more capable replacement for the > > _min_dio_alignment bash helper. > > > > Signed-off-by: Christoph Hellwig <hch@lst.de> > > --- > > src/Makefile | 2 +- > > src/min_dio_alignment.c | 66 +++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 67 insertions(+), 1 deletion(-) > > create mode 100644 src/min_dio_alignment.c > > > > diff --git a/src/Makefile b/src/Makefile > > index 559209be9..b3da59a0e 100644 > > --- a/src/Makefile > > +++ b/src/Makefile > > @@ -34,7 +34,7 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ > > attr_replace_test swapon mkswap t_attr_corruption t_open_tmpfiles \ > > fscrypt-crypt-util bulkstat_null_ocount splice-test chprojid_fail \ > > detached_mounts_propagation ext4_resize t_readdir_3 splice2pipe \ > > - uuid_ioctl t_snapshot_deleted_subvolume fiemap-fault > > + uuid_ioctl t_snapshot_deleted_subvolume fiemap-fault min_dio_alignment Also this program ought to be listed in gitignore. --D > > > > EXTRA_EXECS = dmerror fill2attr fill2fs fill2fs_check scaleread.sh \ > > btrfs_crc32c_forged_name.py popdir.pl popattr.py \ > > diff --git a/src/min_dio_alignment.c b/src/min_dio_alignment.c > > new file mode 100644 > > index 000000000..c3345bfb2 > > --- /dev/null > > +++ b/src/min_dio_alignment.c > > @@ -0,0 +1,66 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Copyright (c) 2024 Christoph Hellwig > > + */ > > +#include <fcntl.h> > > +#include <stdio.h> > > +#include <stdlib.h> > > +#include <unistd.h> > > +#include <sys/mount.h> > > +#include <sys/ioctl.h> > > +#include <sys/stat.h> > > +#include "statx.h" > > + > > +static int min_dio_alignmenent(const char *mntpnt, const char *devname) > > min_dio_alignment > > > +{ > > + struct statx stx = { }; > > + struct stat st; > > + int fd; > > + > > + /* > > + * If the file system supports STATX_DIOALIGN, use the dio_offset_align > > + * member, as that reports exactly the information that we are asking > > + * for. > > + * > > + * STATX_DIOALIGN is only reported on regular files, so use O_TMPFILE > > + * to create one without leaving a trace. > > + */ > > + fd = open(mntpnt, O_TMPFILE | O_RDWR | O_EXCL, 0600); > > + if (fd >= 0 && > > + xfstests_statx(fd, "", AT_EMPTY_PATH, STATX_DIOALIGN, &stx) == 0 && > > + (stx.stx_mask & STATX_DIOALIGN)) > > + return stx.stx_dio_offset_align; > > + > > + /* > > + * If we are on a block device and no explicit aligned is reported, use > > + * the logical block size as a guestimate. > > + */ > > + if (stat(devname, &st) == 0 && S_ISBLK(st.st_mode)) { > > + int dev_fd = open(devname, O_RDONLY); > > + int logical_block_size; > > + > > + if (dev_fd > 0 && > > + fstat(dev_fd, &st) == 0 && > > + S_ISBLK(st.st_mode) && > > + ioctl(dev_fd, BLKSSZGET, &logical_block_size)) { > > + return logical_block_size; > > + } > > + } > > + > > + /* > > + * No support for STATX_DIOALIGN and not a block device: > > + * default to PAGE_SIZE. > > Should we try DIOINFO here as a second to last gasp? > > --D > > > + */ > > + return getpagesize(); > > +} > > + > > +int main(int argc, char **argv) > > +{ > > + if (argc != 3) { > > + fprintf(stderr, "usage: %s mountpoint devicename\n", argv[0]); > > + exit(1); > > + } > > + > > + printf("%d\n", min_dio_alignmenent(argv[1], argv[2])); > > + exit(0); > > +} > > -- > > 2.43.0 > > > > >
On Tue, Aug 13, 2024 at 07:40:04AM -0700, Darrick J. Wong wrote: > > + /* > > + * No support for STATX_DIOALIGN and not a block device: > > + * default to PAGE_SIZE. > > Should we try DIOINFO here as a second to last gasp? Using it is a good idea, and it should probably be second choice. But I'll do that as a separate patch at the end end.
On Tue, Aug 13, 2024 at 07:40:04AM -0700, Darrick J. Wong wrote: > > + /* > > + * No support for STATX_DIOALIGN and not a block device: > > + * default to PAGE_SIZE. > > Should we try DIOINFO here as a second to last gasp? I implemented this last night, but have second thoughts now: DIOINFO is only implemented for XFS, which both implemented STATX_DIOALIGN from the start, and where the block size hack works and is equivalent to the DIOINFO output. So I don't think this buys us anything but costs an extra syscall per invocation. So I plan to drop this again before submission.
diff --git a/src/Makefile b/src/Makefile index 559209be9..b3da59a0e 100644 --- a/src/Makefile +++ b/src/Makefile @@ -34,7 +34,7 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ attr_replace_test swapon mkswap t_attr_corruption t_open_tmpfiles \ fscrypt-crypt-util bulkstat_null_ocount splice-test chprojid_fail \ detached_mounts_propagation ext4_resize t_readdir_3 splice2pipe \ - uuid_ioctl t_snapshot_deleted_subvolume fiemap-fault + uuid_ioctl t_snapshot_deleted_subvolume fiemap-fault min_dio_alignment EXTRA_EXECS = dmerror fill2attr fill2fs fill2fs_check scaleread.sh \ btrfs_crc32c_forged_name.py popdir.pl popattr.py \ diff --git a/src/min_dio_alignment.c b/src/min_dio_alignment.c new file mode 100644 index 000000000..c3345bfb2 --- /dev/null +++ b/src/min_dio_alignment.c @@ -0,0 +1,66 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2024 Christoph Hellwig + */ +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/mount.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include "statx.h" + +static int min_dio_alignmenent(const char *mntpnt, const char *devname) +{ + struct statx stx = { }; + struct stat st; + int fd; + + /* + * If the file system supports STATX_DIOALIGN, use the dio_offset_align + * member, as that reports exactly the information that we are asking + * for. + * + * STATX_DIOALIGN is only reported on regular files, so use O_TMPFILE + * to create one without leaving a trace. + */ + fd = open(mntpnt, O_TMPFILE | O_RDWR | O_EXCL, 0600); + if (fd >= 0 && + xfstests_statx(fd, "", AT_EMPTY_PATH, STATX_DIOALIGN, &stx) == 0 && + (stx.stx_mask & STATX_DIOALIGN)) + return stx.stx_dio_offset_align; + + /* + * If we are on a block device and no explicit aligned is reported, use + * the logical block size as a guestimate. + */ + if (stat(devname, &st) == 0 && S_ISBLK(st.st_mode)) { + int dev_fd = open(devname, O_RDONLY); + int logical_block_size; + + if (dev_fd > 0 && + fstat(dev_fd, &st) == 0 && + S_ISBLK(st.st_mode) && + ioctl(dev_fd, BLKSSZGET, &logical_block_size)) { + return logical_block_size; + } + } + + /* + * No support for STATX_DIOALIGN and not a block device: + * default to PAGE_SIZE. + */ + return getpagesize(); +} + +int main(int argc, char **argv) +{ + if (argc != 3) { + fprintf(stderr, "usage: %s mountpoint devicename\n", argv[0]); + exit(1); + } + + printf("%d\n", min_dio_alignmenent(argv[1], argv[2])); + exit(0); +}
Add a new C program to find the minimum direct I/O alignment. This uses the statx stx_dio_offset_align field if provided, then falls back to the BLKSSZGET ioctl for block backed file systems and finally the page size. It is intended as a more capable replacement for the _min_dio_alignment bash helper. Signed-off-by: Christoph Hellwig <hch@lst.de> --- src/Makefile | 2 +- src/min_dio_alignment.c | 66 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+), 1 deletion(-) create mode 100644 src/min_dio_alignment.c