mirror of
https://github.com/torvalds/linux
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4f819a7899
As in other file systems, we can replace the big kernel lock with a private mutex in isofs. This means we can now access multiple file systems concurrently, but it also means that we serialize readdir and lookup across sleeping operations which previously released the big kernel lock. This should not matter though, as these operations are in practice serialized through the hardware access. The isofs_get_blocks functions now does not take any lock any more, it used to recursively get the BKL. After looking at the code for hours, I convinced myself that it was never needed here anyway, because it only reads constant fields of the inode and writes to a buffer head array that is at this time only visible to the caller. The get_sb and fill_super operations do not need the locking at all because they operate on a file system that is either about to be created or to be destroyed but in either case is not visible to other threads. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
184 lines
6 KiB
C
184 lines
6 KiB
C
#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/exportfs.h>
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#include <linux/iso_fs.h>
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#include <asm/unaligned.h>
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enum isofs_file_format {
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isofs_file_normal = 0,
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isofs_file_sparse = 1,
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isofs_file_compressed = 2,
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};
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/*
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* iso fs inode data in memory
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*/
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struct iso_inode_info {
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unsigned long i_iget5_block;
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unsigned long i_iget5_offset;
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unsigned int i_first_extent;
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unsigned char i_file_format;
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unsigned char i_format_parm[3];
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unsigned long i_next_section_block;
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unsigned long i_next_section_offset;
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off_t i_section_size;
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struct inode vfs_inode;
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};
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/*
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* iso9660 super-block data in memory
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*/
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struct isofs_sb_info {
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unsigned long s_ninodes;
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unsigned long s_nzones;
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unsigned long s_firstdatazone;
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unsigned long s_log_zone_size;
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unsigned long s_max_size;
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int s_rock_offset; /* offset of SUSP fields within SU area */
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unsigned char s_joliet_level;
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unsigned char s_mapping;
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unsigned int s_high_sierra:1;
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unsigned int s_rock:2;
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unsigned int s_utf8:1;
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unsigned int s_cruft:1; /* Broken disks with high byte of length
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* containing junk */
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unsigned int s_nocompress:1;
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unsigned int s_hide:1;
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unsigned int s_showassoc:1;
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unsigned int s_overriderockperm:1;
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unsigned int s_uid_set:1;
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unsigned int s_gid_set:1;
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mode_t s_fmode;
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mode_t s_dmode;
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gid_t s_gid;
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uid_t s_uid;
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struct nls_table *s_nls_iocharset; /* Native language support table */
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struct mutex s_mutex; /* replaces BKL, please remove if possible */
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};
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#define ISOFS_INVALID_MODE ((mode_t) -1)
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static inline struct isofs_sb_info *ISOFS_SB(struct super_block *sb)
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{
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return sb->s_fs_info;
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}
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static inline struct iso_inode_info *ISOFS_I(struct inode *inode)
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{
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return container_of(inode, struct iso_inode_info, vfs_inode);
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}
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static inline int isonum_711(char *p)
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{
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return *(u8 *)p;
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}
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static inline int isonum_712(char *p)
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{
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return *(s8 *)p;
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}
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static inline unsigned int isonum_721(char *p)
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{
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return get_unaligned_le16(p);
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}
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static inline unsigned int isonum_722(char *p)
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{
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return get_unaligned_be16(p);
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}
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static inline unsigned int isonum_723(char *p)
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{
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/* Ignore bigendian datum due to broken mastering programs */
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return get_unaligned_le16(p);
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}
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static inline unsigned int isonum_731(char *p)
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{
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return get_unaligned_le32(p);
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}
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static inline unsigned int isonum_732(char *p)
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{
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return get_unaligned_be32(p);
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}
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static inline unsigned int isonum_733(char *p)
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{
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/* Ignore bigendian datum due to broken mastering programs */
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return get_unaligned_le32(p);
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}
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extern int iso_date(char *, int);
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struct inode; /* To make gcc happy */
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extern int parse_rock_ridge_inode(struct iso_directory_record *, struct inode *);
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extern int get_rock_ridge_filename(struct iso_directory_record *, char *, struct inode *);
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extern int isofs_name_translate(struct iso_directory_record *, char *, struct inode *);
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int get_joliet_filename(struct iso_directory_record *, unsigned char *, struct inode *);
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int get_acorn_filename(struct iso_directory_record *, char *, struct inode *);
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extern struct dentry *isofs_lookup(struct inode *, struct dentry *, struct nameidata *);
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extern struct buffer_head *isofs_bread(struct inode *, sector_t);
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extern int isofs_get_blocks(struct inode *, sector_t, struct buffer_head **, unsigned long);
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extern struct inode *isofs_iget(struct super_block *sb,
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unsigned long block,
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unsigned long offset);
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/* Because the inode number is no longer relevant to finding the
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* underlying meta-data for an inode, we are free to choose a more
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* convenient 32-bit number as the inode number. The inode numbering
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* scheme was recommended by Sergey Vlasov and Eric Lammerts. */
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static inline unsigned long isofs_get_ino(unsigned long block,
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unsigned long offset,
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unsigned long bufbits)
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{
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return (block << (bufbits - 5)) | (offset >> 5);
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}
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/* Every directory can have many redundant directory entries scattered
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* throughout the directory tree. First there is the directory entry
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* with the name of the directory stored in the parent directory.
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* Then, there is the "." directory entry stored in the directory
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* itself. Finally, there are possibly many ".." directory entries
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* stored in all the subdirectories.
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*
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* In order for the NFS get_parent() method to work and for the
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* general consistency of the dcache, we need to make sure the
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* "i_iget5_block" and "i_iget5_offset" all point to exactly one of
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* the many redundant entries for each directory. We normalize the
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* block and offset by always making them point to the "." directory.
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*
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* Notice that we do not use the entry for the directory with the name
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* that is located in the parent directory. Even though choosing this
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* first directory is more natural, it is much easier to find the "."
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* entry in the NFS get_parent() method because it is implicitly
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* encoded in the "extent + ext_attr_length" fields of _all_ the
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* redundant entries for the directory. Thus, it can always be
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* reached regardless of which directory entry you have in hand.
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*
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* This works because the "." entry is simply the first directory
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* record when you start reading the file that holds all the directory
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* records, and this file starts at "extent + ext_attr_length" blocks.
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* Because the "." entry is always the first entry listed in the
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* directories file, the normalized "offset" value is always 0.
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*
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* You should pass the directory entry in "de". On return, "block"
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* and "offset" will hold normalized values. Only directories are
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* affected making it safe to call even for non-directory file
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* types. */
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static inline void
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isofs_normalize_block_and_offset(struct iso_directory_record* de,
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unsigned long *block,
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unsigned long *offset)
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{
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/* Only directories are normalized. */
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if (de->flags[0] & 2) {
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*offset = 0;
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*block = (unsigned long)isonum_733(de->extent)
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+ (unsigned long)isonum_711(de->ext_attr_length);
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}
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}
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extern const struct inode_operations isofs_dir_inode_operations;
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extern const struct file_operations isofs_dir_operations;
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extern const struct address_space_operations isofs_symlink_aops;
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extern const struct export_operations isofs_export_ops;
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