Commit:     f9a14399aea13830d8af6798a53207bb0a900945
Parent:     f98393a64ca1392130724c3acb4e3f325801d2b6
Author:     Peter Zijlstra <[EMAIL PROTECTED]>
AuthorDate: Sun May 6 14:49:55 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon May 7 12:12:55 2007 -0700

    mm: optimize kill_bdev()
    Remove duplicate work in kill_bdev().
    It currently invalidates and then truncates the bdev's mapping.
    invalidate_mapping_pages() will opportunistically remove pages from the
    mapping.  And truncate_inode_pages() will forcefully remove all pages.
    The only thing truncate doesn't do is flush the bh lrus.  So do that
    explicitly.  This avoids (very unlikely) but possible invalid lookup
    results if the same bdev is quickly re-issued.
    It also will prevent extreme kernel latencies which are observed when
    blockdevs which have a large amount of pagecache are unmounted, by avoiding
    invalidate_mapping_pages() on that path.  invalidate_mapping_pages() has no
    cond_resched (it can be called under spinlock), whereas 
    has one.
    [EMAIL PROTECTED]: restore nrpages==0 optimisation]
    Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 fs/block_dev.c              |    6 ++++--
 fs/buffer.c                 |    3 +--
 include/linux/buffer_head.h |    1 +
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 21e59ac..6fe49b9 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -55,10 +55,12 @@ static sector_t max_block(struct block_device *bdev)
        return retval;
-/* Kill _all_ buffers, dirty or not.. */
+/* Kill _all_ buffers and pagecache , dirty or not.. */
 static void kill_bdev(struct block_device *bdev)
-       invalidate_bdev(bdev);
+       if (bdev->bd_inode->i_mapping->nrpages == 0)
+               return;
+       invalidate_bh_lrus();
        truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
diff --git a/fs/buffer.c b/fs/buffer.c
index 630df3e..80291aa 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -44,7 +44,6 @@
 #include <linux/bit_spinlock.h>
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
-static void invalidate_bh_lrus(void);
 #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
@@ -1403,7 +1402,7 @@ static void invalidate_bh_lru(void *arg)
-static void invalidate_bh_lrus(void)
+void invalidate_bh_lrus(void)
        on_each_cpu(invalidate_bh_lru, NULL, 1, 1);
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 632c50b..5c6e128 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -182,6 +182,7 @@ void __brelse(struct buffer_head *);
 void __bforget(struct buffer_head *);
 void __breadahead(struct block_device *, sector_t block, unsigned int size);
 struct buffer_head *__bread(struct block_device *, sector_t block, unsigned 
+void invalidate_bh_lrus(void);
 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
 void free_buffer_head(struct buffer_head * bh);
 void FASTCALL(unlock_buffer(struct buffer_head *bh));
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