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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-07-03 11:30:04 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-07-03 11:30:04 -0700 |
commit | d3acb15a3a1b841dc709c3853ec900170b2478e5 (patch) | |
tree | dc5987350f602559b929232d5b0ea5b89a9f50cb /mm | |
parent | f92a322a63517a798f2da57d56b483a6ae8f45a1 (diff) | |
parent | 6852df1266995c35b8621a95dcb7f91ca11ea409 (diff) | |
download | linux-d3acb15a3a1b841dc709c3853ec900170b2478e5.tar.bz2 |
Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull iov_iter updates from Al Viro:
"iov_iter cleanups and fixes.
There are followups, but this is what had sat in -next this cycle. IMO
the macro forest in there became much thinner and easier to follow..."
* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits)
csum_and_copy_to_pipe_iter(): leave handling of csum_state to caller
clean up copy_mc_pipe_to_iter()
pipe_zero(): we don't need no stinkin' kmap_atomic()...
iov_iter: clean csum_and_copy_...() primitives up a bit
copy_page_from_iter(): don't need kmap_atomic() for kvec/bvec cases
copy_page_to_iter(): don't bother with kmap_atomic() for bvec/kvec cases
iterate_xarray(): only of the first iteration we might get offset != 0
pull handling of ->iov_offset into iterate_{iovec,bvec,xarray}
iov_iter: make iterator callbacks use base and len instead of iovec
iov_iter: make the amount already copied available to iterator callbacks
iov_iter: get rid of separate bvec and xarray callbacks
iov_iter: teach iterate_{bvec,xarray}() about possible short copies
iterate_bvec(): expand bvec.h macro forest, massage a bit
iov_iter: unify iterate_iovec and iterate_kvec
iov_iter: massage iterate_iovec and iterate_kvec to logics similar to iterate_bvec
iterate_and_advance(): get rid of magic in case when n is 0
csum_and_copy_to_iter(): massage into form closer to csum_and_copy_from_iter()
iov_iter: replace iov_iter_copy_from_user_atomic() with iterator-advancing variant
[xarray] iov_iter_npages(): just use DIV_ROUND_UP()
iov_iter_npages(): don't bother with iterate_all_kinds()
...
Diffstat (limited to 'mm')
-rw-r--r-- | mm/filemap.c | 36 |
1 files changed, 15 insertions, 21 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index ac82a93d4f38..d1458ecf2f51 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3642,10 +3642,6 @@ again: * Otherwise there's a nasty deadlock on copying from the * same page as we're writing to, without it being marked * up-to-date. - * - * Not only is this an optimisation, but it is also required - * to check that the address is actually valid, when atomic - * usercopies are used, below. */ if (unlikely(iov_iter_fault_in_readable(i, bytes))) { status = -EFAULT; @@ -3665,33 +3661,31 @@ again: if (mapping_writably_mapped(mapping)) flush_dcache_page(page); - copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); + copied = copy_page_from_iter_atomic(page, offset, bytes, i); flush_dcache_page(page); status = a_ops->write_end(file, mapping, pos, bytes, copied, page, fsdata); - if (unlikely(status < 0)) - break; - copied = status; - + if (unlikely(status != copied)) { + iov_iter_revert(i, copied - max(status, 0L)); + if (unlikely(status < 0)) + break; + } cond_resched(); - iov_iter_advance(i, copied); - if (unlikely(copied == 0)) { + if (unlikely(status == 0)) { /* - * If we were unable to copy any data at all, we must - * fall back to a single segment length write. - * - * If we didn't fallback here, we could livelock - * because not all segments in the iov can be copied at - * once without a pagefault. + * A short copy made ->write_end() reject the + * thing entirely. Might be memory poisoning + * halfway through, might be a race with munmap, + * might be severe memory pressure. */ - bytes = min_t(unsigned long, PAGE_SIZE - offset, - iov_iter_single_seg_count(i)); + if (copied) + bytes = copied; goto again; } - pos += copied; - written += copied; + pos += status; + written += status; balance_dirty_pages_ratelimited(mapping); } while (iov_iter_count(i)); |