[PATCH] shmem: factor out remove_indirect_page()

Split out some common code in shmem_truncate_range() in order to
improve readability (hopefully) and to reduce code duplication.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>

mm/shmem.c | 62 ++++++++++++++++++++++++++++++++++-
1 files changed, 36 insertions(+), 26 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 58da7c150ba6..58ad1159678f 100644
a/mm/shmem.c
+++ b/mm/shmem.c
@@ -531,6 +531,31 @@ static void shmem_free_pages(struct list_head *next)
} while (next);
}

+/**
+ * remove_indirect_page - remove a indirect page from upper layer
+ * @dir: pointer to the indirect page in the upper layer
+ * @page: indirect page to be removed
+ * @needs_lock: pointer to spinlock if needed
+ * @free_list: list which the removed page will be inserted into
+ *
+ * This function removes @page from @dir and insert it into @free_list.
+ * The @page still remains after this function but will not be seen by
+ * other tasks. Finally it will be freed via shmem_free_pages().
+ */
+static void remove_indirect_page(struct page **dir, struct page *page,
+ spinlock_t *needs_lock, struct list_head *free_list)
+{
+ if (needs_lock) {
+ spin_lock(needs_lock);
+ *dir = NULL;
+ spin_unlock(needs_lock);
+ } else {
+ *dir = NULL;
+ }
+
+ list_add(&page->lru, free_list);
+}
+
static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
{
struct shmem_inode_info *info = SHMEM_I(inode);
@@ -582,9 +607,9 @@ static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)

topdir = info->i_indirect;
if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
- info->i_indirect = NULL;
+ remove_indirect_page(&info->i_indirect, topdir, NULL,
+ &pages_to_free);
nr_pages_to_free++;
- list_add(&topdir->lru, &pages_to_free);
}
spin_unlock(&info->lock);

@@ -637,15 +662,10 @@ static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
if (!diroff && !offset && upper_limit >= stage) {
- if (needs_lock) {
- spin_lock(needs_lock);
- *dir = NULL;
- spin_unlock(needs_lock);
- needs_lock = NULL;
- } else
- *dir = NULL;
+ remove_indirect_page(dir, middir, needs_lock,
+ &pages_to_free);
nr_pages_to_free++;
- list_add(&middir->lru, &pages_to_free);
+ needs_lock = NULL;
}
shmem_dir_unmap(dir);
dir = shmem_dir_map(middir);
@@ -672,15 +692,10 @@ static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
if (punch_hole)
needs_lock = &info->lock;
if (upper_limit >= stage) {
- if (needs_lock) {
- spin_lock(needs_lock);
- *dir = NULL;
- spin_unlock(needs_lock);
- needs_lock = NULL;
- } else
- *dir = NULL;
+ remove_indirect_page(dir, middir, needs_lock,
+ &pages_to_free);
nr_pages_to_free++;
- list_add(&middir->lru, &pages_to_free);
+ needs_lock = NULL;
}
shmem_dir_unmap(dir);
cond_resched();
@@ -690,15 +705,10 @@ static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
punch_lock = needs_lock;
subdir = dir[diroff];
if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
- if (needs_lock) {
- spin_lock(needs_lock);
- dir[diroff] = NULL;
- spin_unlock(needs_lock);
- punch_lock = NULL;
- } else
- dir[diroff] = NULL;
+ remove_indirect_page(&dir[diroff], subdir, needs_lock,
+ &pages_to_free);
nr_pages_to_free++;
- list_add(&subdir->lru, &pages_to_free);
+ punch_lock = NULL;
}
if (subdir && page_private(subdir) /* has swap entries */) {
size = limit - idx;
1.7.4

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