Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] fsdax: incorrect size parameter in dax_range_compare_iter causes massive direct access requests --
commit 65ff21563702a9036c338f4961a061d5c576d038 Author: Jianyun Gao <[email protected]> dax: fix wrong error code returned from dax_dedupe_file_range_compare() This commit fixes a bug in dax_dedupe_file_range_compare() where a positive return value was incorrectly propagated on failure. It now correctly returns the negative error code from dax_range_compare_iter(). Link: https://lore.kernel.org/lkml/[email protected]/ > diff --git a/fs/dax.c b/fs/dax.c > index 08adeaed2baf1..97b6212bfa898 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -2254,7 +2254,7 @@ int dax_dedupe_file_range_compare(struct inode *src, > loff_t srcoff, > status = dax_range_compare_iter(&src_iter, &dst_iter, > min(src_iter.len, dst_iter.len), same); > if (status < 0) > - return ret; > + return status; [Severity: High] By correctly propagating the error code here, does this patch now expose a bug in dax_range_compare_iter() that will break dedupe for large offsets? Looking at dax_range_compare_iter() in fs/dax.c, it appears to pass an absolute end offset instead of a length as the size parameter to dax_iomap_direct_access(): static int dax_range_compare_iter(...) { ... ret = dax_iomap_direct_access(smap, pos1, ALIGN(pos1 + len, PAGE_SIZE), &saddr, NULL); ... } When dax_iomap_direct_access() receives this size parameter, it converts it via PHYS_PFN() and interprets the massive absolute offset as a relative length: fs/dax.c:dax_iomap_direct_access() { ... length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), DAX_ACCESS, kaddr, pfnp); ... } This requests an out-of-bounds mapping length from the underlying block driver (up to pos1 + len instead of just len), which typically fails with -EINVAL or -EIO for offsets that exceed device bounds. Since this patch changes the behavior from a silent pseudo-success to an explicit failure, will standard deduplication at non-zero offsets now consistently fail when dax_range_compare_iter() erroneously asks for an enormous number of pages? > src_iter.status = dst_iter.status = status; > } > return ret; -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
