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-rw-r--r--fs/fat/nfs.c292
1 files changed, 292 insertions, 0 deletions
diff --git a/fs/fat/nfs.c b/fs/fat/nfs.c
new file mode 100644
index 0000000000..3626eb585a
--- /dev/null
+++ b/fs/fat/nfs.c
@@ -0,0 +1,292 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* fs/fat/nfs.c
+ */
+
+#include <linux/exportfs.h>
+#include "fat.h"
+
+struct fat_fid {
+ u32 i_gen;
+ u32 i_pos_low;
+ u16 i_pos_hi;
+ u16 parent_i_pos_hi;
+ u32 parent_i_pos_low;
+ u32 parent_i_gen;
+};
+
+#define FAT_FID_SIZE_WITHOUT_PARENT 3
+#define FAT_FID_SIZE_WITH_PARENT (sizeof(struct fat_fid)/sizeof(u32))
+
+/*
+ * Look up a directory inode given its starting cluster.
+ */
+static struct inode *fat_dget(struct super_block *sb, int i_logstart)
+{
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+ struct hlist_head *head;
+ struct msdos_inode_info *i;
+ struct inode *inode = NULL;
+
+ head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
+ spin_lock(&sbi->dir_hash_lock);
+ hlist_for_each_entry(i, head, i_dir_hash) {
+ BUG_ON(i->vfs_inode.i_sb != sb);
+ if (i->i_logstart != i_logstart)
+ continue;
+ inode = igrab(&i->vfs_inode);
+ if (inode)
+ break;
+ }
+ spin_unlock(&sbi->dir_hash_lock);
+ return inode;
+}
+
+static struct inode *fat_ilookup(struct super_block *sb, u64 ino, loff_t i_pos)
+{
+ if (MSDOS_SB(sb)->options.nfs == FAT_NFS_NOSTALE_RO)
+ return fat_iget(sb, i_pos);
+
+ else {
+ if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
+ return NULL;
+ return ilookup(sb, ino);
+ }
+}
+
+static struct inode *__fat_nfs_get_inode(struct super_block *sb,
+ u64 ino, u32 generation, loff_t i_pos)
+{
+ struct inode *inode = fat_ilookup(sb, ino, i_pos);
+
+ if (inode && generation && (inode->i_generation != generation)) {
+ iput(inode);
+ inode = NULL;
+ }
+ if (inode == NULL && MSDOS_SB(sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
+ struct buffer_head *bh = NULL;
+ struct msdos_dir_entry *de ;
+ sector_t blocknr;
+ int offset;
+ fat_get_blknr_offset(MSDOS_SB(sb), i_pos, &blocknr, &offset);
+ bh = sb_bread(sb, blocknr);
+ if (!bh) {
+ fat_msg(sb, KERN_ERR,
+ "unable to read block(%llu) for building NFS inode",
+ (llu)blocknr);
+ return inode;
+ }
+ de = (struct msdos_dir_entry *)bh->b_data;
+ /* If a file is deleted on server and client is not updated
+ * yet, we must not build the inode upon a lookup call.
+ */
+ if (IS_FREE(de[offset].name))
+ inode = NULL;
+ else
+ inode = fat_build_inode(sb, &de[offset], i_pos);
+ brelse(bh);
+ }
+
+ return inode;
+}
+
+static struct inode *fat_nfs_get_inode(struct super_block *sb,
+ u64 ino, u32 generation)
+{
+
+ return __fat_nfs_get_inode(sb, ino, generation, 0);
+}
+
+static int
+fat_encode_fh_nostale(struct inode *inode, __u32 *fh, int *lenp,
+ struct inode *parent)
+{
+ int len = *lenp;
+ struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+ struct fat_fid *fid = (struct fat_fid *) fh;
+ loff_t i_pos;
+ int type = FILEID_FAT_WITHOUT_PARENT;
+
+ if (parent) {
+ if (len < FAT_FID_SIZE_WITH_PARENT) {
+ *lenp = FAT_FID_SIZE_WITH_PARENT;
+ return FILEID_INVALID;
+ }
+ } else {
+ if (len < FAT_FID_SIZE_WITHOUT_PARENT) {
+ *lenp = FAT_FID_SIZE_WITHOUT_PARENT;
+ return FILEID_INVALID;
+ }
+ }
+
+ i_pos = fat_i_pos_read(sbi, inode);
+ *lenp = FAT_FID_SIZE_WITHOUT_PARENT;
+ fid->i_gen = inode->i_generation;
+ fid->i_pos_low = i_pos & 0xFFFFFFFF;
+ fid->i_pos_hi = (i_pos >> 32) & 0xFFFF;
+ if (parent) {
+ i_pos = fat_i_pos_read(sbi, parent);
+ fid->parent_i_pos_hi = (i_pos >> 32) & 0xFFFF;
+ fid->parent_i_pos_low = i_pos & 0xFFFFFFFF;
+ fid->parent_i_gen = parent->i_generation;
+ type = FILEID_FAT_WITH_PARENT;
+ *lenp = FAT_FID_SIZE_WITH_PARENT;
+ }
+
+ return type;
+}
+
+/*
+ * Map a NFS file handle to a corresponding dentry.
+ * The dentry may or may not be connected to the filesystem root.
+ */
+static struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+ fat_nfs_get_inode);
+}
+
+static struct dentry *fat_fh_to_dentry_nostale(struct super_block *sb,
+ struct fid *fh, int fh_len,
+ int fh_type)
+{
+ struct inode *inode = NULL;
+ struct fat_fid *fid = (struct fat_fid *)fh;
+ loff_t i_pos;
+
+ switch (fh_type) {
+ case FILEID_FAT_WITHOUT_PARENT:
+ if (fh_len < FAT_FID_SIZE_WITHOUT_PARENT)
+ return NULL;
+ break;
+ case FILEID_FAT_WITH_PARENT:
+ if (fh_len < FAT_FID_SIZE_WITH_PARENT)
+ return NULL;
+ break;
+ default:
+ return NULL;
+ }
+ i_pos = fid->i_pos_hi;
+ i_pos = (i_pos << 32) | (fid->i_pos_low);
+ inode = __fat_nfs_get_inode(sb, 0, fid->i_gen, i_pos);
+
+ return d_obtain_alias(inode);
+}
+
+/*
+ * Find the parent for a file specified by NFS handle.
+ * This requires that the handle contain the i_ino of the parent.
+ */
+static struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+ fat_nfs_get_inode);
+}
+
+static struct dentry *fat_fh_to_parent_nostale(struct super_block *sb,
+ struct fid *fh, int fh_len,
+ int fh_type)
+{
+ struct inode *inode = NULL;
+ struct fat_fid *fid = (struct fat_fid *)fh;
+ loff_t i_pos;
+
+ if (fh_len < FAT_FID_SIZE_WITH_PARENT)
+ return NULL;
+
+ switch (fh_type) {
+ case FILEID_FAT_WITH_PARENT:
+ i_pos = fid->parent_i_pos_hi;
+ i_pos = (i_pos << 32) | (fid->parent_i_pos_low);
+ inode = __fat_nfs_get_inode(sb, 0, fid->parent_i_gen, i_pos);
+ break;
+ }
+
+ return d_obtain_alias(inode);
+}
+
+/*
+ * 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.
+ *
+ * On entry, the caller holds d_inode(child_dir)->i_mutex.
+ */
+static struct dentry *fat_get_parent(struct dentry *child_dir)
+{
+ struct super_block *sb = child_dir->d_sb;
+ 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(d_inode(child_dir), &bh, &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);
+
+ return d_obtain_alias(parent_inode);
+}
+
+const struct export_operations fat_export_ops = {
+ .fh_to_dentry = fat_fh_to_dentry,
+ .fh_to_parent = fat_fh_to_parent,
+ .get_parent = fat_get_parent,
+};
+
+const struct export_operations fat_export_ops_nostale = {
+ .encode_fh = fat_encode_fh_nostale,
+ .fh_to_dentry = fat_fh_to_dentry_nostale,
+ .fh_to_parent = fat_fh_to_parent_nostale,
+ .get_parent = fat_get_parent,
+};
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 02:55:25 +0000