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yaml --- r: 330132 b: refs/heads/master c: 21b6633 h: refs/heads/master v: v3
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Steven J. Magnani
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Linus Torvalds
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Oct 5, 2012
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,2 +1,2 @@ | ||
| --- | ||
| refs/heads/master: 4b63709861e431e73f0be6b83f420fdd8fc518f5 | ||
| refs/heads/master: 21b6633d516c4f5d03ec02ede6374e320191003f |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,151 @@ | ||
| /* fs/fat/nfs.c | ||
| * | ||
| * This software is licensed under the terms of the GNU General Public | ||
| * License version 2, as published by the Free Software Foundation, and | ||
| * may be copied, distributed, and modified under those terms. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| */ | ||
|
|
||
| #include <linux/exportfs.h> | ||
| #include "fat.h" | ||
|
|
||
| /* | ||
| * a FAT file handle with fhtype 3 is | ||
| * 0/ i_ino - for fast, reliable lookup if still in the cache | ||
| * 1/ i_generation - to see if i_ino is still valid | ||
| * bit 0 == 0 iff directory | ||
| * 2/ i_pos(8-39) - if ino has changed, but still in cache | ||
| * 3/ i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos | ||
| * 4/ i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc | ||
| * | ||
| * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum | ||
| * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits | ||
| * of i_logstart is used to store the directory entry offset. | ||
| */ | ||
|
|
||
| int | ||
| fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent) | ||
| { | ||
| int len = *lenp; | ||
| struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); | ||
| loff_t i_pos; | ||
|
|
||
| if (len < 5) { | ||
| *lenp = 5; | ||
| return 255; /* no room */ | ||
| } | ||
|
|
||
| i_pos = fat_i_pos_read(sbi, inode); | ||
| *lenp = 5; | ||
| fh[0] = inode->i_ino; | ||
| fh[1] = inode->i_generation; | ||
| fh[2] = i_pos >> 8; | ||
| fh[3] = ((i_pos & 0xf0) << 24) | MSDOS_I(inode)->i_logstart; | ||
| fh[4] = (i_pos & 0x0f) << 28; | ||
| if (parent) | ||
| fh[4] |= MSDOS_I(parent)->i_logstart; | ||
| return 3; | ||
| } | ||
|
|
||
| static int fat_is_valid_fh(int fh_len, int fh_type) | ||
| { | ||
| return ((fh_len >= 5) && (fh_type == 3)); | ||
| } | ||
|
|
||
| /** | ||
| * Map a NFS file handle to a corresponding dentry. | ||
| * The dentry may or may not be connected to the filesystem root. | ||
| */ | ||
| struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid, | ||
| int fh_len, int fh_type) | ||
| { | ||
| struct inode *inode = NULL; | ||
| u32 *fh = fid->raw; | ||
| loff_t i_pos; | ||
| unsigned long i_ino; | ||
| __u32 i_generation; | ||
| int i_logstart; | ||
|
|
||
| if (!fat_is_valid_fh(fh_len, fh_type)) | ||
| return NULL; | ||
|
|
||
| i_ino = fh[0]; | ||
| i_generation = fh[1]; | ||
| i_logstart = fh[3] & 0x0fffffff; | ||
|
|
||
| /* Try i_ino lookup first - fastest and most reliable */ | ||
| inode = ilookup(sb, i_ino); | ||
| if (inode && (inode->i_generation != i_generation)) { | ||
| iput(inode); | ||
| inode = NULL; | ||
| } | ||
| if (!inode) { | ||
| i_pos = (loff_t)fh[2] << 8; | ||
| i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28); | ||
|
|
||
| /* try 2 - see if i_pos is in F-d-c | ||
| * require i_logstart to be the same | ||
| * Will fail if you truncate and then re-write | ||
| */ | ||
|
|
||
| inode = fat_iget(sb, i_pos); | ||
| if (inode && MSDOS_I(inode)->i_logstart != i_logstart) { | ||
| iput(inode); | ||
| inode = NULL; | ||
| } | ||
| } | ||
|
|
||
| /* | ||
| * For now, do nothing if the inode is not found. | ||
| * | ||
| * What we could do is: | ||
| * | ||
| * - follow the file starting at fh[4], and record the ".." entry, | ||
| * and the name of the fh[2] entry. | ||
| * - then follow the ".." file finding the next step up. | ||
| * | ||
| * This way we build a path to the root of the tree. If this works, we | ||
| * lookup the path and so get this inode into the cache. Finally try | ||
| * the fat_iget lookup again. If that fails, then we are totally out | ||
| * of luck. But all that is for another day | ||
| */ | ||
| return d_obtain_alias(inode); | ||
| } | ||
|
|
||
| /* | ||
| * Find the parent for a directory that is not currently connected to | ||
| * the filesystem root. | ||
| * | ||
| * On entry, the caller holds child_dir->d_inode->i_mutex. | ||
| */ | ||
| 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; | ||
| loff_t i_pos; | ||
| struct dentry *parent; | ||
| struct inode *inode; | ||
| int err; | ||
|
|
||
| lock_super(sb); | ||
|
|
||
| err = fat_get_dotdot_entry(child_dir->d_inode, &bh, &de, &i_pos); | ||
| if (err) { | ||
| parent = ERR_PTR(err); | ||
| goto out; | ||
| } | ||
| inode = fat_build_inode(sb, de, i_pos); | ||
|
|
||
| parent = d_obtain_alias(inode); | ||
| out: | ||
| brelse(bh); | ||
| unlock_super(sb); | ||
|
|
||
| return parent; | ||
| } |