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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-07-10 08:53:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-07-10 08:53:21 -0700 |
| commit | d02b0478c1acb00e9d9ee40810627eba5745d94b (patch) | |
| tree | 9c522f00c574d8641c0242dd606ac30ea7909582 /mm | |
| parent | f4c8824cbcc64524905f83388eb1139747829756 (diff) | |
| parent | 20f829999c38b18e3d17f9e40dea3a28f721fac4 (diff) | |
| download | lwn-d02b0478c1acb00e9d9ee40810627eba5745d94b.tar.gz lwn-d02b0478c1acb00e9d9ee40810627eba5745d94b.zip | |
Merge tag 'gfs2-v5.8-rc4.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 fixes from Andreas Gruenbacher:
"Fix gfs2 readahead deadlocks by adding a IOCB_NOIO flag that allows
gfs2 to use the generic fiel read iterator functions without having to
worry about being called back while holding locks".
* tag 'gfs2-v5.8-rc4.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: Rework read and page fault locking
fs: Add IOCB_NOIO flag for generic_file_read_iter
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/filemap.c | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index f0ae9a6308cb..385759c4ce4b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2028,7 +2028,7 @@ find_page: page = find_get_page(mapping, index); if (!page) { - if (iocb->ki_flags & IOCB_NOWAIT) + if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) goto would_block; page_cache_sync_readahead(mapping, ra, filp, @@ -2038,6 +2038,10 @@ find_page: goto no_cached_page; } if (PageReadahead(page)) { + if (iocb->ki_flags & IOCB_NOIO) { + put_page(page); + goto out; + } page_cache_async_readahead(mapping, ra, filp, page, index, last_index - index); @@ -2160,6 +2164,11 @@ page_not_up_to_date_locked: } readpage: + if (iocb->ki_flags & IOCB_NOIO) { + unlock_page(page); + put_page(page); + goto would_block; + } /* * A previous I/O error may have been due to temporary * failures, eg. multipath errors. @@ -2249,9 +2258,19 @@ EXPORT_SYMBOL_GPL(generic_file_buffered_read); * * This is the "read_iter()" routine for all filesystems * that can use the page cache directly. + * + * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall + * be returned when no data can be read without waiting for I/O requests + * to complete; it doesn't prevent readahead. + * + * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O + * requests shall be made for the read or for readahead. When no data + * can be read, -EAGAIN shall be returned. When readahead would be + * triggered, a partial, possibly empty read shall be returned. + * * Return: * * number of bytes copied, even for partial reads - * * negative error code if nothing was read + * * negative error code (or 0 if IOCB_NOIO) if nothing was read */ ssize_t generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) |