From: Chao Liu <liuc...@coolpad.com>

This patch is a cleanup:
1. Merge __drop_largest_extent() since it has only one caller.
2. Introduce __unlock_tree_with_checking_largest() and
   __drop_largest_extent() to help manage largest and largest_update
   in extent_tree.

Signed-off-by: Chao Liu <liuc...@coolpad.com>
---
v2: Make sure et->largest_updated gets updated within &et->lock.
    Thanks to Chao Yu for pointing out.
---
 fs/f2fs/extent_cache.c | 66 ++++++++++++++++++++----------------------
 fs/f2fs/f2fs.h         |  4 +--
 2 files changed, 33 insertions(+), 37 deletions(-)

diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 0e2d49140c07f..cfc69621a8a26 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -19,6 +19,12 @@
 #include "node.h"
 #include <trace/events/f2fs.h>
 
+static void __drop_largest_extent(struct extent_tree *et)
+{
+       et->largest.len = 0;
+       et->largest_updated = true;
+}
+
 bool sanity_check_extent_cache(struct inode *inode)
 {
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
@@ -35,8 +41,7 @@ bool sanity_check_extent_cache(struct inode *inode)
 
        /* Let's drop, if checkpoint got corrupted. */
        if (is_set_ckpt_flags(sbi, CP_ERROR_FLAG)) {
-               ei->len = 0;
-               et->largest_updated = true;
+               __drop_largest_extent(et);
                return true;
        }
 
@@ -310,6 +315,8 @@ static void __detach_extent_node(struct f2fs_sb_info *sbi,
 
        if (et->cached_en == en)
                et->cached_en = NULL;
+
+       /* keep the largest as we can still use it */
        kmem_cache_free(extent_node_slab, en);
 }
 
@@ -385,15 +392,6 @@ static unsigned int __free_extent_tree(struct f2fs_sb_info 
*sbi,
        return count - atomic_read(&et->node_cnt);
 }
 
-static void __drop_largest_extent(struct extent_tree *et,
-                                       pgoff_t fofs, unsigned int len)
-{
-       if (fofs < et->largest.fofs + et->largest.len &&
-                       fofs + len > et->largest.fofs) {
-               et->largest.len = 0;
-               et->largest_updated = true;
-       }
-}
 
 void f2fs_init_read_extent_tree(struct inode *inode, struct page *ipage)
 {
@@ -601,6 +599,19 @@ static struct extent_node *__insert_extent_tree(struct 
f2fs_sb_info *sbi,
        return en;
 }
 
+static void __unlock_tree_with_checking_largest(struct extent_tree *et,
+                                               struct inode *inode)
+{
+       if (et->type == EX_READ && et->largest_updated) {
+               et->largest_updated = false;
+               write_unlock(&et->lock);
+               f2fs_mark_inode_dirty_sync(inode, true);
+               return;
+       }
+
+       write_unlock(&et->lock);
+}
+
 static void __update_extent_tree_range(struct inode *inode,
                        struct extent_info *tei, enum extent_type type)
 {
@@ -612,7 +623,6 @@ static void __update_extent_tree_range(struct inode *inode,
        struct rb_node **insert_p = NULL, *insert_parent = NULL;
        unsigned int fofs = tei->fofs, len = tei->len;
        unsigned int end = fofs + len;
-       bool updated = false;
        bool leftmost = false;
 
        if (!et)
@@ -636,11 +646,10 @@ static void __update_extent_tree_range(struct inode 
*inode,
                prev = et->largest;
                dei.len = 0;
 
-               /*
-                * drop largest extent before lookup, in case it's already
-                * been shrunk from extent tree
-                */
-               __drop_largest_extent(et, fofs, len);
+               /* updates may cause largest extent cache to become invalid */
+               if (fofs < et->largest.fofs + et->largest.len &&
+                   fofs + len > et->largest.fofs)
+                       __drop_largest_extent(et);
        }
 
        /* 1. lookup first extent node in range [fofs, fofs + len - 1] */
@@ -733,8 +742,7 @@ static void __update_extent_tree_range(struct inode *inode,
                if (dei.len >= 1 &&
                                prev.len < F2FS_MIN_EXTENT_LEN &&
                                et->largest.len < F2FS_MIN_EXTENT_LEN) {
-                       et->largest.len = 0;
-                       et->largest_updated = true;
+                       __drop_largest_extent(et);
                        set_inode_flag(inode, FI_NO_EXTENT);
                }
        }
@@ -742,10 +750,6 @@ static void __update_extent_tree_range(struct inode *inode,
        if (is_inode_flag_set(inode, FI_NO_EXTENT))
                __free_extent_tree(sbi, et);
 
-       if (et->largest_updated) {
-               et->largest_updated = false;
-               updated = true;
-       }
        goto out_read_extent_cache;
 update_age_extent_cache:
        if (!tei->last_blocks)
@@ -757,10 +761,7 @@ static void __update_extent_tree_range(struct inode *inode,
                __insert_extent_tree(sbi, et, &ei,
                                        insert_p, insert_parent, leftmost);
 out_read_extent_cache:
-       write_unlock(&et->lock);
-
-       if (updated)
-               f2fs_mark_inode_dirty_sync(inode, true);
+       __unlock_tree_with_checking_largest(et, inode);
 }
 
 #ifdef CONFIG_F2FS_FS_COMPRESSION
@@ -1092,7 +1093,6 @@ static void __drop_extent_tree(struct inode *inode, enum 
extent_type type)
 {
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
-       bool updated = false;
 
        if (!__may_extent_tree(inode, type))
                return;
@@ -1101,14 +1101,10 @@ static void __drop_extent_tree(struct inode *inode, 
enum extent_type type)
        __free_extent_tree(sbi, et);
        if (type == EX_READ) {
                set_inode_flag(inode, FI_NO_EXTENT);
-               if (et->largest.len) {
-                       et->largest.len = 0;
-                       updated = true;
-               }
+               if (et->largest.len)
+                       __drop_largest_extent(et);
        }
-       write_unlock(&et->lock);
-       if (updated)
-               f2fs_mark_inode_dirty_sync(inode, true);
+       __unlock_tree_with_checking_largest(et, inode);
 }
 
 void f2fs_drop_extent_tree(struct inode *inode)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d372bedb0fe4e..da02e120e5ea6 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -665,7 +665,7 @@ struct extent_tree {
 
 struct extent_tree_info {
        struct radix_tree_root extent_tree_root;/* cache extent cache entries */
-       struct mutex extent_tree_lock;  /* locking extent radix tree */
+       struct mutex extent_tree_lock;          /* locking extent radix tree */
        struct list_head extent_list;           /* lru list for shrinker */
        spinlock_t extent_lock;                 /* locking extent lru list */
        atomic_t total_ext_tree;                /* extent tree count */
@@ -766,7 +766,7 @@ enum {
        FI_ACL_MODE,            /* indicate acl mode */
        FI_NO_ALLOC,            /* should not allocate any blocks */
        FI_FREE_NID,            /* free allocated nide */
-       FI_NO_EXTENT,           /* not to use the extent cache */
+       FI_NO_EXTENT,           /* not to use the read extent cache */
        FI_INLINE_XATTR,        /* used for inline xattr */
        FI_INLINE_DATA,         /* used for inline data*/
        FI_INLINE_DENTRY,       /* used for inline dentry */
-- 
2.25.1



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