[PATCH 2/2] f2fs: fix to limit gc_pin_file_threshold

From: Chao Yu
Date: Mon May 06 2024 - 06:46:12 EST


type of f2fs_inode.i_gc_failures, f2fs_inode_info.i_gc_failures, and
f2fs_sb_info.gc_pin_file_threshold is __le16, unsigned int, and u64,
so it will cause truncation during comparison and persistence.

Unifying variable of these three variables to unsigned short, and
add an upper boundary limitation for gc_pin_file_threshold.

Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-fs-f2fs | 2 +-
fs/f2fs/f2fs.h | 4 ++--
fs/f2fs/file.c | 11 ++++++-----
fs/f2fs/gc.h | 1 +
fs/f2fs/sysfs.c | 7 +++++++
5 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 1a4d83953379..cad6c3dc1f9c 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -331,7 +331,7 @@ Date: January 2018
Contact: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Description: This indicates how many GC can be failed for the pinned
file. If it exceeds this, F2FS doesn't guarantee its pinning
- state. 2048 trials is set by default.
+ state. 2048 trials is set by default, and 65535 as maximum.

What: /sys/fs/f2fs/<disk>/extension_list
Date: February 2018
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 400ff8e1abe0..3dff45cd6cde 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -813,7 +813,7 @@ struct f2fs_inode_info {
unsigned char i_dir_level; /* use for dentry level for large dir */
union {
unsigned int i_current_depth; /* only for directory depth */
- unsigned int i_gc_failures; /* for gc failure statistic */
+ unsigned short i_gc_failures; /* for gc failure statistic */
};
unsigned int i_pino; /* parent inode number */
umode_t i_acl_mode; /* keep file acl mode temporarily */
@@ -1672,7 +1672,7 @@ struct f2fs_sb_info {
unsigned long long skipped_gc_rwsem; /* FG_GC only */

/* threshold for gc trials on pinned files */
- u64 gc_pin_file_threshold;
+ unsigned short gc_pin_file_threshold;
struct f2fs_rwsem pin_sem;

/* maximum # of trials to find a victim segment for SSR and GC */
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 200cafc75dce..1b1b08923f7d 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3194,16 +3194,17 @@ int f2fs_pin_file_control(struct inode *inode, bool inc)
struct f2fs_inode_info *fi = F2FS_I(inode);
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

- /* Use i_gc_failures for normal file as a risk signal. */
- if (inc)
- f2fs_i_gc_failures_write(inode, fi->i_gc_failures + 1);
-
- if (fi->i_gc_failures > sbi->gc_pin_file_threshold) {
+ if (fi->i_gc_failures >= sbi->gc_pin_file_threshold) {
f2fs_warn(sbi, "%s: Enable GC = ino %lx after %x GC trials",
__func__, inode->i_ino, fi->i_gc_failures);
clear_inode_flag(inode, FI_PIN_FILE);
return -EAGAIN;
}
+
+ /* Use i_gc_failures for normal file as a risk signal. */
+ if (inc)
+ f2fs_i_gc_failures_write(inode, fi->i_gc_failures + 1);
+
return 0;
}

diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
index 9c0d06c4d19a..a8ea3301b815 100644
--- a/fs/f2fs/gc.h
+++ b/fs/f2fs/gc.h
@@ -26,6 +26,7 @@
#define LIMIT_FREE_BLOCK 40 /* percentage over invalid + free space */

#define DEF_GC_FAILED_PINNED_FILES 2048
+#define MAX_GC_FAILED_PINNED_FILES USHRT_MAX

/* Search max. number of dirty segments to select a victim segment */
#define DEF_MAX_VICTIM_SEARCH 4096 /* covers 8GB */
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 7aa3844e7a80..09d3ecfaa4f1 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -681,6 +681,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
return count;
}

+ if (!strcmp(a->attr.name, "gc_pin_file_threshold")) {
+ if (t > MAX_GC_FAILED_PINNED_FILES)
+ return -EINVAL;
+ sbi->gc_pin_file_threshold = t;
+ return count;
+ }
+
if (!strcmp(a->attr.name, "gc_reclaimed_segments")) {
if (t != 0)
return -EINVAL;
--
2.40.1