On Tue, Jun 24, 2025 at 02:26:18PM -0400, Jeff Layton wrote: > On Tue, 2025-06-24 at 07:14 -0700, Christoph Hellwig wrote: > > On Sun, Jun 22, 2025 at 08:32:18PM +0800, ying chen wrote: > > > Normally, user space returns immediately after writing data to the > > > buffer cache. However, if an error occurs during the actual disk > > > write operation, data loss may ensue, and there is no way to report > > > this error back to user space immediately. Current kernels may report > > > writeback errors when fsync() is called, but frequent invocations of > > > fsync() can degrade performance. Therefore, a new sysctl > > > fs.xfs.report_writeback_error_on_read is introduced, which, when set > > > to 1, reports writeback errors when read() is called. This allows user > > > space to be notified of writeback errors more promptly. > > > > That's really kernel wide policy and not something magic done by a > > single file system. > > ...not to mention that getting an error back on a read for a prior > writeback error would be completely unexpected by most applications. Well. It's somewhat understandable: write() (returns success) writeback happens, error logged memory pressure evicts folio read() brings folio into page cache attempt to read contents fails, error returned I'm not sure it's a good solution, but it's plausible.
