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Wong" To: Brian Foster Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, hch@infradead.org, willy@infradead.org Subject: Re: [PATCH v3 7/7] xfs: error tag to force zeroing on debug kernels Message-ID: <20250715052444.GP2672049@frogsfrogsfrogs> References: <20250714204122.349582-1-bfoster@redhat.com> <20250714204122.349582-8-bfoster@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250714204122.349582-8-bfoster@redhat.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: A39C4180004 X-Stat-Signature: anbi78pzqd9bprty4gyft46wxyg7pzgp X-HE-Tag: 1752557085-894673 X-HE-Meta: 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 m97PWJCr OlIwz1u8Jw2MvEnr8uV5/PSnfR8JknYhJ8YhdeukI22Ta8bzdQw7ERiG9ahEWeIFMDjTiEBdyC2+8tCJ48bPSLVG6hywqubQUTRUGG1hYtgaIc4d6naz7B8zpNkglZyN6821DffLX9sM0TurHRNP+0XDHRaaqVbf47BLDUf1AE14jMLoVItdY0lobtaEj0fUEN8a/uSAayVxQxeLVG0jpWT3Hl3MKBsgSgnrU8+TIsVVFxuW+zQ9fHFLMhF2NAwl9vD7Zhu4EydJzfuTJdiYh4sSux8cZ/Jig5+Qz5fbJ0eKITyCCTK2LxHnDOw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 14, 2025 at 04:41:22PM -0400, Brian Foster wrote: > iomap_zero_range() has to cover various corner cases that are > difficult to test on production kernels because it is used in fairly > limited use cases. For example, it is currently only used by XFS and > mostly only in partial block zeroing cases. > > While it's possible to test most of these functional cases, we can > provide more robust test coverage by co-opting fallocate zero range > to invoke zeroing of the entire range instead of the more efficient > block punch/allocate sequence. Add an errortag to occasionally > invoke forced zeroing. > > Signed-off-by: Brian Foster > Reviewed-by: Christoph Hellwig > --- > fs/xfs/libxfs/xfs_errortag.h | 4 +++- > fs/xfs/xfs_error.c | 3 +++ > fs/xfs/xfs_file.c | 26 ++++++++++++++++++++------ > 3 files changed, 26 insertions(+), 7 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_errortag.h b/fs/xfs/libxfs/xfs_errortag.h > index a53c5d40e084..33ca3fc2ca88 100644 > --- a/fs/xfs/libxfs/xfs_errortag.h > +++ b/fs/xfs/libxfs/xfs_errortag.h > @@ -65,7 +65,8 @@ > #define XFS_ERRTAG_WRITE_DELAY_MS 43 > #define XFS_ERRTAG_EXCHMAPS_FINISH_ONE 44 > #define XFS_ERRTAG_METAFILE_RESV_CRITICAL 45 > -#define XFS_ERRTAG_MAX 46 > +#define XFS_ERRTAG_FORCE_ZERO_RANGE 46 > +#define XFS_ERRTAG_MAX 47 > > /* > * Random factors for above tags, 1 means always, 2 means 1/2 time, etc. > @@ -115,5 +116,6 @@ > #define XFS_RANDOM_WRITE_DELAY_MS 3000 > #define XFS_RANDOM_EXCHMAPS_FINISH_ONE 1 > #define XFS_RANDOM_METAFILE_RESV_CRITICAL 4 > +#define XFS_RANDOM_FORCE_ZERO_RANGE 4 > > #endif /* __XFS_ERRORTAG_H_ */ > diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c > index dbd87e137694..00c0c391c329 100644 > --- a/fs/xfs/xfs_error.c > +++ b/fs/xfs/xfs_error.c > @@ -64,6 +64,7 @@ static unsigned int xfs_errortag_random_default[] = { > XFS_RANDOM_WRITE_DELAY_MS, > XFS_RANDOM_EXCHMAPS_FINISH_ONE, > XFS_RANDOM_METAFILE_RESV_CRITICAL, > + XFS_RANDOM_FORCE_ZERO_RANGE, > }; > > struct xfs_errortag_attr { > @@ -183,6 +184,7 @@ XFS_ERRORTAG_ATTR_RW(wb_delay_ms, XFS_ERRTAG_WB_DELAY_MS); > XFS_ERRORTAG_ATTR_RW(write_delay_ms, XFS_ERRTAG_WRITE_DELAY_MS); > XFS_ERRORTAG_ATTR_RW(exchmaps_finish_one, XFS_ERRTAG_EXCHMAPS_FINISH_ONE); > XFS_ERRORTAG_ATTR_RW(metafile_resv_crit, XFS_ERRTAG_METAFILE_RESV_CRITICAL); > +XFS_ERRORTAG_ATTR_RW(force_zero_range, XFS_ERRTAG_FORCE_ZERO_RANGE); > > static struct attribute *xfs_errortag_attrs[] = { > XFS_ERRORTAG_ATTR_LIST(noerror), > @@ -230,6 +232,7 @@ static struct attribute *xfs_errortag_attrs[] = { > XFS_ERRORTAG_ATTR_LIST(write_delay_ms), > XFS_ERRORTAG_ATTR_LIST(exchmaps_finish_one), > XFS_ERRORTAG_ATTR_LIST(metafile_resv_crit), > + XFS_ERRORTAG_ATTR_LIST(force_zero_range), > NULL, > }; > ATTRIBUTE_GROUPS(xfs_errortag); > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 0b41b18debf3..c865f9555b77 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -27,6 +27,8 @@ > #include "xfs_file.h" > #include "xfs_aops.h" > #include "xfs_zone_alloc.h" > +#include "xfs_error.h" > +#include "xfs_errortag.h" > > #include > #include > @@ -1269,13 +1271,25 @@ xfs_falloc_zero_range( > if (error) > return error; > > - error = xfs_free_file_space(XFS_I(inode), offset, len, ac); > - if (error) > - return error; > + /* > + * Zero range implements a full zeroing mechanism but is only used in > + * limited situations. It is more efficient to allocate unwritten > + * extents than to perform zeroing here, so use an errortag to randomly > + * force zeroing on DEBUG kernels for added test coverage. > + */ > + if (XFS_TEST_ERROR(false, XFS_I(inode)->i_mount, > + XFS_ERRTAG_FORCE_ZERO_RANGE)) { > + error = xfs_zero_range(XFS_I(inode), offset, len, ac, NULL); Isn't this basically the ultra slow version fallback version of FALLOC_FL_WRITE_ZEROES ? --D > + } else { > + error = xfs_free_file_space(XFS_I(inode), offset, len, ac); > + if (error) > + return error; > > - len = round_up(offset + len, blksize) - round_down(offset, blksize); > - offset = round_down(offset, blksize); > - error = xfs_alloc_file_space(XFS_I(inode), offset, len); > + len = round_up(offset + len, blksize) - > + round_down(offset, blksize); > + offset = round_down(offset, blksize); > + error = xfs_alloc_file_space(XFS_I(inode), offset, len); > + } > if (error) > return error; > return xfs_falloc_setsize(file, new_size); > -- > 2.50.0 > >