Re: [f2fs-dev] [PATCH 1/1] f2fs: allocate trace path buffer from names_cache
From: Chao Yu
Date: Wed Apr 19 2023 - 21:10:52 EST
On 2023/4/20 3:45, Jaegeuk Kim wrote:
On 04/19, Jaegeuk Kim wrote:
On 04/19, Chao Yu wrote:
On 2023/4/19 0:07, Jaegeuk Kim wrote:
On 04/18, Chao Yu wrote:
On 2023/4/14 18:43, Wu Bo wrote:
It would be better to use the dedicated slab to store path.
Signed-off-by: Wu Bo <bo.wu@xxxxxxxx>
---
fs/f2fs/file.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 15dabeac4690..27137873958f 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4361,7 +4361,7 @@ static void f2fs_trace_rw_file_path(struct kiocb *iocb, size_t count, int rw)
struct inode *inode = file_inode(iocb->ki_filp);
char *buf, *path;
- buf = f2fs_kmalloc(F2FS_I_SB(inode), PATH_MAX, GFP_KERNEL);
+ buf = __getname();
How about:
buf = f2fs_kmem_cache_alloc(names_cachep, GFP_KERNEL, NULL, F2FS_I_SB(inode));
This looks like a hack using names_cachep?
names_cachep was exported in fs.h.
I think that's for __getname() in general, which doesn't indicate you can hack.
No one is using like that.
$ grep names_cachep fs/* -R
fs/dcache.c:struct kmem_cache *names_cachep __read_mostly;
fs/dcache.c:EXPORT_SYMBOL(names_cachep);
fs/dcache.c: names_cachep = kmem_cache_create_usercopy("names_cache", PATH_MAX, 0,
$ grep __getname fs/* -R
fs/ceph/mds_client.c: path = __getname();
fs/cifs/cifsproto.h: return __getname();
fs/dcache.c:/* SLAB cache for __getname() consumers */
fs/d_path.c: char *page = __getname();
fs/exfat/dir.c: nb->lfn = __getname();
fs/f2fs/file.c: buf = __getname();
fs/fat/dir.c: *unicode = __getname();
fs/fat/namei_vfat.c: uname = __getname();
fs/hostfs/hostfs_kern.c: char *name = __getname();
fs/namei.c: result = __getname();
fs/namei.c: result = __getname();
fs/ntfs3/dir.c: name = __getname();
fs/ntfs3/xattr.c: buf = __getname();
fs/ntfs3/inode.c: new_de = __getname();
fs/ntfs3/inode.c: de = __getname();
fs/ntfs3/inode.c: de = __getname();
fs/ntfs3/namei.c: struct cpu_str *uni = __getname();
fs/ntfs3/namei.c: de = __getname();
fs/ntfs3/namei.c: struct cpu_str *uni = __getname();
fs/ntfs3/namei.c: uni = __getname();
fs/ntfs3/namei.c: uni1 = __getname();
fs/vboxsf/utils.c: * Returns a shfl_string allocated through __getname (must be freed using
fs/vboxsf/utils.c: buf = __getname();
fs/vboxsf/utils.c: shfl_path = __getname();
Using f2fs_kmem_cache_alloc is able to inject malloc error.
But here is a trace event, is it ok to inject error in a trace path?
Yes, the fail path handling is very simple, so it's fine to leave it
as it is.
Reviewed-by: Chao Yu <chao@xxxxxxxxxx>
What is this for?
Oh, I mean I'm okay w/ original patch, because f2fs_trace_rw_file_path()
doesn't have complicated error handling.
If we want to keep the error injection, how about this?
Both original patch or below patch w/ fault injection is fine to me.
Free feel to add rvb tag of me. :)
Thanks,
Signed-off-by: Wu Bo <bo.wu@xxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
fs/f2fs/f2fs.h | 13 +++++++++++++
fs/f2fs/file.c | 4 ++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 6cae94d51821..d87044516fe9 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3347,6 +3347,19 @@ static inline void *f2fs_kmalloc(struct f2fs_sb_info *sbi,
return kmalloc(size, flags);
}
+static inline void *f2fs_getname(struct f2fs_sb_info *sbi)
+{
+ if (time_to_inject(sbi, FAULT_KMALLOC))
+ return NULL;
+
+ return __getname();
+}
+
+static inline void f2fs_putname(char *buf)
+{
+ __putname(buf);
+}
+
static inline void *f2fs_kzalloc(struct f2fs_sb_info *sbi,
size_t size, gfp_t flags)
{
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 1b4411271f54..5ac53d2627d2 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4372,7 +4372,7 @@ static void f2fs_trace_rw_file_path(struct kiocb *iocb, size_t count, int rw)
struct inode *inode = file_inode(iocb->ki_filp);
char *buf, *path;
- buf = f2fs_kmalloc(F2FS_I_SB(inode), PATH_MAX, GFP_KERNEL);
+ buf = f2fs_getname(F2FS_I_SB(inode));
if (!buf)
return;
path = dentry_path_raw(file_dentry(iocb->ki_filp), buf, PATH_MAX);
@@ -4385,7 +4385,7 @@ static void f2fs_trace_rw_file_path(struct kiocb *iocb, size_t count, int rw)
trace_f2fs_dataread_start(inode, iocb->ki_pos, count,
current->pid, path, current->comm);
free_buf:
- kfree(buf);
+ f2fs_putname(buf);
}
static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)