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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250421105026.19577-2-chentaotao@didiglobal.com> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 9C1C0140004 X-Stat-Signature: hf3w3keaqgczwikaf9a14drzit83w8ty X-Rspam-User: X-HE-Tag: 1747194704-389441 X-HE-Meta: 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 hCB1MFmI dJY/ytNodxIFZj6ERXFlp53zuF4Ub62oDEUEnaSyAlKF7c7pKxE20xBTWlzXCx0pS0ArGy2zQ808F8wPcULFvDQLJ+bOF283EOEbtRdCU66Wridb7/HEX32kS42Sv7dODa8SDfxfW1onnH75FZ7dLORTV976OAlwzKEbOoBi3o/UG8VY0l/VHER2i5XM3qTM7RS7qz3TPCwr1uNlArafUoVIaR1OsZUP0gBhy+9OgLR19UIY= 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, Apr 21, 2025 at 10:50:30AM +0000, 陈涛涛 Taotao Chen wrote: > diff --git a/mm/filemap.c b/mm/filemap.c > index 7b90cbeb4a1a..9174b6310f0b 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -4087,7 +4087,11 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) > size_t offset; /* Offset into folio */ > size_t bytes; /* Bytes to write to folio */ > size_t copied; /* Bytes copied from user */ > - void *fsdata = NULL; > + /* > + * Initialize fsdata with iocb flags pointer so that filesystems > + * can check ki_flags (like IOCB_DONTCACHE) in write operations. > + */ > + void *fsdata = &iocb->ki_flags; Unfortunately, this is't safe. There may very well be code paths which depend on fsdata being initialized to NULL before calling write_begin(). In fact in the patch 2/3 in this series, ext4_write_end() will get confused in the non-delayed allocation case, since ext4_write_begin() doesn't force fsdata to be not be &iocb->ki_flags, and this will cause ext4_write_end() to potentially get confused and do the wrong thing. I understand that it would be a lot more inconvenient change the function signature of write_begin() to pass through iocb->ki_fags via a new parameter. But I think that probably is the best way to go. Cheers, - Ted