124 lines
4.5 KiB
Diff
124 lines
4.5 KiB
Diff
From: Miklos Szeredi <mszeredi@suse.cz>
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Date: Wed, 24 Sep 2014 17:09:11 +0200
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Subject: fuse: honour max_read and max_write in direct_io mode
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Origin: https://git.kernel.org/linus/2c80929c4c4d54e568b07ab85877d5fd38f4b02f
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The third argument of fuse_get_user_pages() "nbytesp" refers to the number of
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bytes a caller asked to pack into fuse request. This value may be lesser
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than capacity of fuse request or iov_iter. So fuse_get_user_pages() must
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ensure that *nbytesp won't grow.
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Now, when helper iov_iter_get_pages() performs all hard work of extracting
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pages from iov_iter, it can be done by passing properly calculated
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"maxsize" to the helper.
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The other caller of iov_iter_get_pages() (dio_refill_pages()) doesn't need
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this capability, so pass LONG_MAX as the maxsize argument here.
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Fixes: c9c37e2e6378 ("fuse: switch to iov_iter_get_pages()")
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Reported-by: Werner Baumann <werner.baumann@onlinehome.de>
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Tested-by: Maxim Patlasov <mpatlasov@parallels.com>
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Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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---
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fs/direct-io.c | 2 +-
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fs/fuse/file.c | 1 +
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include/linux/uio.h | 2 +-
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mm/iov_iter.c | 14 +++++++++-----
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4 files changed, 12 insertions(+), 7 deletions(-)
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diff --git a/fs/direct-io.c b/fs/direct-io.c
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index c311640..e181b6b 100644
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--- a/fs/direct-io.c
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+++ b/fs/direct-io.c
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@@ -158,7 +158,7 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
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{
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ssize_t ret;
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- ret = iov_iter_get_pages(sdio->iter, dio->pages, DIO_PAGES,
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+ ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES,
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&sdio->from);
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if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) {
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diff --git a/fs/fuse/file.c b/fs/fuse/file.c
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index 912061a..caa8d95 100644
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--- a/fs/fuse/file.c
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+++ b/fs/fuse/file.c
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@@ -1305,6 +1305,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
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size_t start;
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ssize_t ret = iov_iter_get_pages(ii,
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&req->pages[req->num_pages],
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+ *nbytesp - nbytes,
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req->max_pages - req->num_pages,
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&start);
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if (ret < 0)
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diff --git a/include/linux/uio.h b/include/linux/uio.h
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index 48d64e6..290fbf0 100644
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--- a/include/linux/uio.h
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+++ b/include/linux/uio.h
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@@ -84,7 +84,7 @@ unsigned long iov_iter_alignment(const struct iov_iter *i);
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void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
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unsigned long nr_segs, size_t count);
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ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
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- unsigned maxpages, size_t *start);
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+ size_t maxsize, unsigned maxpages, size_t *start);
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ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
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size_t maxsize, size_t *start);
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int iov_iter_npages(const struct iov_iter *i, int maxpages);
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diff --git a/mm/iov_iter.c b/mm/iov_iter.c
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index ab88dc0..9a09f20 100644
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--- a/mm/iov_iter.c
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+++ b/mm/iov_iter.c
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@@ -310,7 +310,7 @@ void iov_iter_init(struct iov_iter *i, int direction,
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EXPORT_SYMBOL(iov_iter_init);
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static ssize_t get_pages_iovec(struct iov_iter *i,
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- struct page **pages, unsigned maxpages,
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+ struct page **pages, size_t maxsize, unsigned maxpages,
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size_t *start)
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{
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size_t offset = i->iov_offset;
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@@ -323,6 +323,8 @@ static ssize_t get_pages_iovec(struct iov_iter *i,
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len = iov->iov_len - offset;
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if (len > i->count)
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len = i->count;
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+ if (len > maxsize)
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+ len = maxsize;
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addr = (unsigned long)iov->iov_base + offset;
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len += *start = addr & (PAGE_SIZE - 1);
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if (len > maxpages * PAGE_SIZE)
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@@ -588,13 +590,15 @@ static unsigned long alignment_bvec(const struct iov_iter *i)
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}
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static ssize_t get_pages_bvec(struct iov_iter *i,
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- struct page **pages, unsigned maxpages,
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+ struct page **pages, size_t maxsize, unsigned maxpages,
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size_t *start)
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{
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const struct bio_vec *bvec = i->bvec;
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size_t len = bvec->bv_len - i->iov_offset;
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if (len > i->count)
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len = i->count;
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+ if (len > maxsize)
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+ len = maxsize;
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/* can't be more than PAGE_SIZE */
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*start = bvec->bv_offset + i->iov_offset;
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@@ -711,13 +715,13 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
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EXPORT_SYMBOL(iov_iter_alignment);
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ssize_t iov_iter_get_pages(struct iov_iter *i,
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- struct page **pages, unsigned maxpages,
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+ struct page **pages, size_t maxsize, unsigned maxpages,
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size_t *start)
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{
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if (i->type & ITER_BVEC)
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- return get_pages_bvec(i, pages, maxpages, start);
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+ return get_pages_bvec(i, pages, maxsize, maxpages, start);
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else
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- return get_pages_iovec(i, pages, maxpages, start);
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+ return get_pages_iovec(i, pages, maxsize, maxpages, start);
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}
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EXPORT_SYMBOL(iov_iter_get_pages);
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