fat (exportfs): rebuild inode if ilookup() fails

If the cache lookups fail,use the i_pos value to find the directory entry
of the inode and rebuild the inode.Since this involves accessing the FAT
media, do this only if the nostale_ro nfs mount option is specified.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ravishankar N <ravi.n1@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 27f49f4fa0d3..971ba7d549da 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -443,12 +443,25 @@ static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
         return 0;
 }
 
+static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
+{
+        if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
+                mutex_lock(&sbi->nfs_build_inode_lock);
+}
+
+static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
+{
+        if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
+                mutex_unlock(&sbi->nfs_build_inode_lock);
+}
+
 struct inode *fat_build_inode(struct super_block *sb,
                         struct msdos_dir_entry *de, loff_t i_pos)
 {
         struct inode *inode;
         int err;
 
+        fat_lock_build_inode(MSDOS_SB(sb));
         inode = fat_iget(sb, i_pos);
         if (inode)
                 goto out;
@@ -468,6 +481,7 @@ struct inode *fat_build_inode(struct super_block *sb,
         fat_attach(inode, i_pos);
         insert_inode_hash(inode);
 out:
+        fat_unlock_build_inode(MSDOS_SB(sb));
         return inode;
 }
 
@@ -1247,6 +1261,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
         sb->s_magic = MSDOS_SUPER_MAGIC;
         sb->s_op = &fat_sops;
         sb->s_export_op = &fat_export_ops;
+        mutex_init(&sbi->nfs_build_inode_lock);
         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
                              DEFAULT_RATELIMIT_BURST);