From: Matthew Wilcox Add associated infrastructure such as sync_page_killable and fatal_signal_pending. Use lock_page_killable in do_generic_mapping_read() to allow us to kill `cat' of a file on an NFS-mounted filesystem. Signed-off-by: Matthew Wilcox Cc: Trond Myklebust Cc: "J. Bruce Fields" Cc: Nick Piggin Signed-off-by: Andrew Morton --- include/linux/pagemap.h | 14 ++++++++++++++ include/linux/sched.h | 9 ++++++++- kernel/signal.c | 5 +++++ mm/filemap.c | 25 +++++++++++++++++++++---- 4 files changed, 48 insertions(+), 5 deletions(-) diff -puN include/linux/pagemap.h~add-lock_page_killable include/linux/pagemap.h --- a/include/linux/pagemap.h~add-lock_page_killable +++ a/include/linux/pagemap.h @@ -157,6 +157,7 @@ static inline pgoff_t linear_page_index( } extern void FASTCALL(__lock_page(struct page *page)); +extern int FASTCALL(__lock_page_killable(struct page *page)); extern void FASTCALL(__lock_page_nosync(struct page *page)); extern void FASTCALL(unlock_page(struct page *page)); @@ -171,6 +172,19 @@ static inline void lock_page(struct page } /* + * lock_page_killable is like lock_page but can be interrupted by fatal + * signals. It returns 0 if it locked the page and -EINTR if it was + * killed while waiting. + */ +static inline int lock_page_killable(struct page *page) +{ + might_sleep(); + if (TestSetPageLocked(page)) + return __lock_page_killable(page); + return 0; +} + +/* * lock_page_nosync should only be used if we can't pin the page's inode. * Doesn't play quite so well with block device plugging. */ diff -puN include/linux/sched.h~add-lock_page_killable include/linux/sched.h --- a/include/linux/sched.h~add-lock_page_killable +++ a/include/linux/sched.h @@ -1862,7 +1862,14 @@ static inline int signal_pending(struct { return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING)); } - + +extern int FASTCALL(__fatal_signal_pending(struct task_struct *p)); + +static inline int fatal_signal_pending(struct task_struct *p) +{ + return signal_pending(p) && __fatal_signal_pending(p); +} + static inline int need_resched(void) { return unlikely(test_thread_flag(TIF_NEED_RESCHED)); diff -puN kernel/signal.c~add-lock_page_killable kernel/signal.c --- a/kernel/signal.c~add-lock_page_killable +++ a/kernel/signal.c @@ -994,6 +994,11 @@ void zap_other_threads(struct task_struc } } +int fastcall __fatal_signal_pending(struct task_struct *tsk) +{ + return sigismember(&tsk->pending.signal, SIGKILL); +} + /* * Must be called under rcu_read_lock() or with tasklist_lock read-held. */ diff -puN mm/filemap.c~add-lock_page_killable mm/filemap.c --- a/mm/filemap.c~add-lock_page_killable +++ a/mm/filemap.c @@ -172,6 +172,12 @@ static int sync_page(void *word) return 0; } +static int sync_page_killable(void *word) +{ + sync_page(word); + return fatal_signal_pending(current) ? -EINTR : 0; +} + /** * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range * @mapping: address space structure to write @@ -576,6 +582,14 @@ void fastcall __lock_page(struct page *p } EXPORT_SYMBOL(__lock_page); +int fastcall __lock_page_killable(struct page *page) +{ + DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); + + return __wait_on_bit_lock(page_waitqueue(page), &wait, + sync_page_killable, TASK_KILLABLE); +} + /* * Variant of lock_page that does not require the caller to hold a reference * on the page's mapping. @@ -967,7 +981,8 @@ page_ok: page_not_up_to_date: /* Get exclusive access to the page ... */ - lock_page(page); + if (lock_page_killable(page)) + goto readpage_eio; /* Did it get truncated before we got the lock? */ if (!page->mapping) { @@ -995,7 +1010,8 @@ readpage: } if (!PageUptodate(page)) { - lock_page(page); + if (lock_page_killable(page)) + goto readpage_eio; if (!PageUptodate(page)) { if (page->mapping == NULL) { /* @@ -1006,15 +1022,16 @@ readpage: goto find_page; } unlock_page(page); - error = -EIO; shrink_readahead_size_eio(filp, ra); - goto readpage_error; + goto readpage_eio; } unlock_page(page); } goto page_ok; +readpage_eio: + error = -EIO; readpage_error: /* UHHUH! A synchronous read error occurred. Report it */ desc->error = error; _