On 2025/8/15 0:54, Darrick J. Wong wrote: > On Wed, Aug 13, 2025 at 10:42:50AM +0800, Zhang Yi wrote: >> From: Zhang Yi <yi.zh...@huawei.com> >> >> The Linux kernel (since version 6.17) supports FALLOC_FL_WRITE_ZEROES in >> fallocate(2). Add support for FALLOC_FL_WRITE_ZEROES support to the >> fallocate utility by introducing a new 'fwzero' command in the xfs_io >> tool. >> >> Link: >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=278c7d9b5e0c >> Signed-off-by: Zhang Yi <yi.zh...@huawei.com> >> --- >> v1->v2: >> - Minor description modification to align with the kernel. >> >> io/prealloc.c | 36 ++++++++++++++++++++++++++++++++++++ >> man/man8/xfs_io.8 | 6 ++++++ >> 2 files changed, 42 insertions(+) >> >> diff --git a/io/prealloc.c b/io/prealloc.c >> index 8e968c9f..9a64bf53 100644 >> --- a/io/prealloc.c >> +++ b/io/prealloc.c >> @@ -30,6 +30,10 @@ >> #define FALLOC_FL_UNSHARE_RANGE 0x40 >> #endif >> >> +#ifndef FALLOC_FL_WRITE_ZEROES >> +#define FALLOC_FL_WRITE_ZEROES 0x80 >> +#endif >> + >> static cmdinfo_t allocsp_cmd; >> static cmdinfo_t freesp_cmd; >> static cmdinfo_t resvsp_cmd; >> @@ -41,6 +45,7 @@ static cmdinfo_t fcollapse_cmd; >> static cmdinfo_t finsert_cmd; >> static cmdinfo_t fzero_cmd; >> static cmdinfo_t funshare_cmd; >> +static cmdinfo_t fwzero_cmd; >> >> static int >> offset_length( >> @@ -377,6 +382,27 @@ funshare_f( >> return 0; >> } >> >> +static int >> +fwzero_f( >> + int argc, >> + char **argv) >> +{ >> + xfs_flock64_t segment; >> + int mode = FALLOC_FL_WRITE_ZEROES; > > Shouldn't this take a -k to add FALLOC_FL_KEEP_SIZE like fzero? >
Since allocating blocks with written extents beyond the inode size is not permitted, the FALLOC_FL_WRITE_ZEROES flag cannot be used together with the FALLOC_FL_KEEP_SIZE. Thanks, Yi. > (The code otherwise looks fine to me) > > --D > >> + >> + if (!offset_length(argv[1], argv[2], &segment)) { >> + exitcode = 1; >> + return 0; >> + } >> + >> + if (fallocate(file->fd, mode, segment.l_start, segment.l_len)) { >> + perror("fallocate"); >> + exitcode = 1; >> + return 0; >> + } >> + return 0; >> +} >> + >> void >> prealloc_init(void) >> { >> @@ -489,4 +515,14 @@ prealloc_init(void) >> funshare_cmd.oneline = >> _("unshares shared blocks within the range"); >> add_command(&funshare_cmd); >> + >> + fwzero_cmd.name = "fwzero"; >> + fwzero_cmd.cfunc = fwzero_f; >> + fwzero_cmd.argmin = 2; >> + fwzero_cmd.argmax = 2; >> + fwzero_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK; >> + fwzero_cmd.args = _("off len"); >> + fwzero_cmd.oneline = >> + _("zeroes space and eliminates holes by allocating and submitting write >> zeroes"); >> + add_command(&fwzero_cmd); >> } >> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8 >> index b0dcfdb7..0a673322 100644 >> --- a/man/man8/xfs_io.8 >> +++ b/man/man8/xfs_io.8 >> @@ -550,6 +550,12 @@ With the >> .B -k >> option, use the FALLOC_FL_KEEP_SIZE flag as well. >> .TP >> +.BI fwzero " offset length" >> +Call fallocate with FALLOC_FL_WRITE_ZEROES flag as described in the >> +.BR fallocate (2) >> +manual page to allocate and zero blocks within the range by submitting write >> +zeroes. >> +.TP >> .BI zero " offset length" >> Call xfsctl with >> .B XFS_IOC_ZERO_RANGE >> -- >> 2.39.2 >> >>