tmpfs: fix regression hang in fallocate undo
[ Upstream commitwifi-calibration7f55656703
] The well-spotted fallocate undo fix is good in most cases, but not when fallocate failed on the very first page. index 0 then passes lend -1 to shmem_undo_range(), and that has two bad effects: (a) that it will undo every fallocation throughout the file, unrestricted by the current range; but more importantly (b) it can cause the undo to hang, because lend -1 is treated as truncation, which makes it keep on retrying until every page has gone, but those already fully instantiated will never go away. Big thank you to xfstests generic/269 which demonstrates this. Fixes:b9b4bb26af
("tmpfs: don't undo fallocate past its last page") Cc: stable@vger.kernel.org Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
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b7aa372fec
commit
116c75f642
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@ -2137,9 +2137,11 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
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NULL);
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NULL);
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if (error) {
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if (error) {
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/* Remove the !PageUptodate pages we added */
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/* Remove the !PageUptodate pages we added */
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shmem_undo_range(inode,
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if (index > start) {
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(loff_t)start << PAGE_CACHE_SHIFT,
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shmem_undo_range(inode,
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((loff_t)index << PAGE_CACHE_SHIFT) - 1, true);
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(loff_t)start << PAGE_CACHE_SHIFT,
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((loff_t)index << PAGE_CACHE_SHIFT) - 1, true);
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}
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goto undone;
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goto undone;
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}
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}
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