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Date: Tue, 22 Jan 2013 19:31:45 +0900
From: Namjae Jeon <linkinjeon@...il.com>
To: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc: akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org,
Namjae Jeon <namjae.jeon@...sung.com>,
Ravishankar N <ravi.n1@...sung.com>,
Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH v5 7/8] fat (exportfs): rebuild directory-inode if
fat_dget() fails
2013/1/20, OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>:
> Namjae Jeon <linkinjeon@...il.com> writes:
>
>> We rewrite patch as your suggestion using dummy inode. Would please
>> you review below patch code ?
>
> Looks like good as initial. Clean and shorter.
>
> Next is, we have to think about race. I.e. if real inode was made, what
> happens? Is there no race?
Hi OGAWA.
Although checking several routines to check hang case you said, I
didn't find anything.
And There is no any race on test result also. Am I missing something ?
Let me know your opinion.
Thanks.
>
> Thanks.
>
>> Subject: [PATCH] fat (exportfs): rebuild directory-inode if fat_dget()
>> fails
>>
>> This patch enables rebuilding of directory inodes which are not present
>> in the cache.This is done by traversing the disk clusters to find the
>> directory entry of the parent directory and using its i_pos to build the
>> inode.
>>
>> Do this only if the "nostale_ro" nfs mount option is specified.
>>
>> ---
>> fs/fat/dir.c | 23 +++++++++++++++++++++++
>> fs/fat/fat.h | 3 +++
>> fs/fat/inode.c | 2 +-
>> fs/fat/nfs.c | 52
>> +++++++++++++++++++++++++++++++++++++++++++++++++++-
>> 4 files changed, 78 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/fat/dir.c b/fs/fat/dir.c
>> index 695c15c..ac97f34 100644
>> --- a/fs/fat/dir.c
>> +++ b/fs/fat/dir.c
>> @@ -975,6 +975,29 @@ int fat_scan(struct inode *dir, const unsigned char
>> *name,
>>
>> EXPORT_SYMBOL_GPL(fat_scan);
>>
>> +/*
>> + * Scans a directory for a given logstart.
>> + * Returns an error code or zero.
>> + */
>> +int fat_scan_logstart(struct inode *dir, int i_logstart,
>> + struct fat_slot_info *sinfo)
>> +{
>> + struct super_block *sb = dir->i_sb;
>> +
>> + sinfo->slot_off = 0;
>> + sinfo->bh = NULL;
>> + while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
>> + &sinfo->de) >= 0) {
>> + if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
>> + sinfo->slot_off -= sizeof(*sinfo->de);
>> + sinfo->nr_slots = 1;
>> + sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
>> + return 0;
>> + }
>> + }
>> + return -ENOENT;
>> +}
>> +
>> static int __fat_remove_entries(struct inode *dir, loff_t pos, int
>> nr_slots)
>> {
>> struct super_block *sb = dir->i_sb;
>> diff --git a/fs/fat/fat.h b/fs/fat/fat.h
>> index 73f15b8..d882c01 100644
>> --- a/fs/fat/fat.h
>> +++ b/fs/fat/fat.h
>> @@ -291,6 +291,8 @@ extern int fat_dir_empty(struct inode *dir);
>> extern int fat_subdirs(struct inode *dir);
>> extern int fat_scan(struct inode *dir, const unsigned char *name,
>> struct fat_slot_info *sinfo);
>> +extern int fat_scan_logstart(struct inode *dir, int i_logstart,
>> + struct fat_slot_info *sinfo);
>> extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head
>> **bh,
>> struct msdos_dir_entry **de);
>> extern int fat_alloc_new_dir(struct inode *dir, struct timespec *ts);
>> @@ -370,6 +372,7 @@ extern int fat_fill_super(struct super_block *sb,
>> void *data, int silent,
>>
>> extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
>> struct inode *i2);
>> +extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry
>> *de);
>> static inline unsigned long fat_dir_hash(int logstart)
>> {
>> return hash_32(logstart, FAT_HASH_BITS);
>> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
>> index 491320b..c4c286a 100644
>> --- a/fs/fat/inode.c
>> +++ b/fs/fat/inode.c
>> @@ -384,7 +384,7 @@ static int fat_calc_dir_size(struct inode *inode)
>> }
>>
>> /* doesn't deal with root inode */
>> -static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry
>> *de)
>> +int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
>> {
>> struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
>> int error;
>> diff --git a/fs/fat/nfs.c b/fs/fat/nfs.c
>> index 08ff9fa..e94da33 100644
>> --- a/fs/fat/nfs.c
>> +++ b/fs/fat/nfs.c
>> @@ -213,6 +213,53 @@ static struct dentry
>> *fat_fh_to_parent_nostale(struct super_block *sb,
>> }
>>
>> /*
>> + * Rebuild the parent for a directory that is not connected
>> + * to the filesystem root
>> + */
>> +static
>> +struct inode *fat_rebuild_parent(struct super_block *sb, int
>> parent_logstart)
>> +{
>> + int search_clus, clus_to_match;
>> + struct msdos_dir_entry *de;
>> + struct inode *parent = NULL;
>> + struct inode *dummy_grand_parent = NULL;
>> + struct fat_slot_info sinfo;
>> + struct msdos_sb_info *sbi = MSDOS_SB(sb);
>> + sector_t blknr = fat_clus_to_blknr(sbi, parent_logstart);
>> + struct buffer_head *parent_bh = sb_bread(sb, blknr);
>> + if (!parent_bh) {
>> + fat_msg(sb, KERN_ERR,
>> + "unable to read cluster of parent directory");
>> + return NULL;
>> + }
>> +
>> + de = (struct msdos_dir_entry *) parent_bh->b_data;
>> + clus_to_match = fat_get_start(sbi, &de[0]);
>> + search_clus = fat_get_start(sbi, &de[1]);
>> +
>> + dummy_grand_parent = fat_dget(sb, search_clus);
>> + if (!dummy_grand_parent) {
>> + dummy_grand_parent = new_inode(sb);
>> + if (!dummy_grand_parent) {
>> + brelse(parent_bh);
>> + return parent;
>> + }
>> +
>> + dummy_grand_parent->i_ino = iunique(sb, MSDOS_ROOT_INO);
>> + fat_fill_inode(dummy_grand_parent, &de[1]);
>> + MSDOS_I(dummy_grand_parent)->i_pos = -1;
>> + }
>> +
>> + if (!fat_scan_logstart(dummy_grand_parent, clus_to_match, &sinfo))
>> + parent = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
>> +
>> + brelse(parent_bh);
>> + iput(dummy_grand_parent);
>> +
>> + return parent;
>> +}
>> +
>> +/*
>> * Find the parent for a directory that is not currently connected to
>> * the filesystem root.
>> *
>> @@ -224,10 +271,13 @@ static struct dentry *fat_get_parent(struct
>> dentry *child_dir)
>> struct buffer_head *bh = NULL;
>> struct msdos_dir_entry *de;
>> struct inode *parent_inode = NULL;
>> + struct msdos_sb_info *sbi = MSDOS_SB(sb);
>>
>> if (!fat_get_dotdot_entry(child_dir->d_inode, &bh, &de)) {
>> - int parent_logstart = fat_get_start(MSDOS_SB(sb), de);
>> + int parent_logstart = fat_get_start(sbi, de);
>> parent_inode = fat_dget(sb, parent_logstart);
>> + if (!parent_inode && sbi->options.nfs == FAT_NFS_NOSTALE_RO)
>> + parent_inode = fat_rebuild_parent(sb, parent_logstart);
>> }
>> brelse(bh);
>
> --
> OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
>
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