diff options
Diffstat (limited to 'fs/gfs2/dir.c')
| -rw-r--r-- | fs/gfs2/dir.c | 144 |
1 files changed, 75 insertions, 69 deletions
diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c index eb68cdd41d48..ffc1beff6703 100644 --- a/fs/gfs2/dir.c +++ b/fs/gfs2/dir.c @@ -8,61 +8,59 @@ */ /* -* Implements Extendible Hashing as described in: -* "Extendible Hashing" by Fagin, et al in -* __ACM Trans. on Database Systems__, Sept 1979. -* -* -* Here's the layout of dirents which is essentially the same as that of ext2 -* within a single block. The field de_name_len is the number of bytes -* actually required for the name (no null terminator). The field de_rec_len -* is the number of bytes allocated to the dirent. The offset of the next -* dirent in the block is (dirent + dirent->de_rec_len). When a dirent is -* deleted, the preceding dirent inherits its allocated space, ie -* prev->de_rec_len += deleted->de_rec_len. Since the next dirent is obtained -* by adding de_rec_len to the current dirent, this essentially causes the -* deleted dirent to get jumped over when iterating through all the dirents. -* -* When deleting the first dirent in a block, there is no previous dirent so -* the field de_ino is set to zero to designate it as deleted. When allocating -* a dirent, gfs2_dirent_alloc iterates through the dirents in a block. If the -* first dirent has (de_ino == 0) and de_rec_len is large enough, this first -* dirent is allocated. Otherwise it must go through all the 'used' dirents -* searching for one in which the amount of total space minus the amount of -* used space will provide enough space for the new dirent. -* -* There are two types of blocks in which dirents reside. In a stuffed dinode, -* the dirents begin at offset sizeof(struct gfs2_dinode) from the beginning of -* the block. In leaves, they begin at offset sizeof(struct gfs2_leaf) from the -* beginning of the leaf block. The dirents reside in leaves when -* -* dip->i_di.di_flags & GFS2_DIF_EXHASH is true -* -* Otherwise, the dirents are "linear", within a single stuffed dinode block. -* -* When the dirents are in leaves, the actual contents of the directory file are -* used as an array of 64-bit block pointers pointing to the leaf blocks. The -* dirents are NOT in the directory file itself. There can be more than one block -* pointer in the array that points to the same leaf. In fact, when a directory -* is first converted from linear to exhash, all of the pointers point to the -* same leaf. -* -* When a leaf is completely full, the size of the hash table can be -* doubled unless it is already at the maximum size which is hard coded into -* GFS2_DIR_MAX_DEPTH. After that, leaves are chained together in a linked list, -* but never before the maximum hash table size has been reached. -*/ + * Implements Extendible Hashing as described in: + * "Extendible Hashing" by Fagin, et al in + * __ACM Trans. on Database Systems__, Sept 1979. + * + * + * Here's the layout of dirents which is essentially the same as that of ext2 + * within a single block. The field de_name_len is the number of bytes + * actually required for the name (no null terminator). The field de_rec_len + * is the number of bytes allocated to the dirent. The offset of the next + * dirent in the block is (dirent + dirent->de_rec_len). When a dirent is + * deleted, the preceding dirent inherits its allocated space, ie + * prev->de_rec_len += deleted->de_rec_len. Since the next dirent is obtained + * by adding de_rec_len to the current dirent, this essentially causes the + * deleted dirent to get jumped over when iterating through all the dirents. + * + * When deleting the first dirent in a block, there is no previous dirent so + * the field de_ino is set to zero to designate it as deleted. When allocating + * a dirent, gfs2_dirent_alloc iterates through the dirents in a block. If the + * first dirent has (de_ino == 0) and de_rec_len is large enough, this first + * dirent is allocated. Otherwise it must go through all the 'used' dirents + * searching for one in which the amount of total space minus the amount of + * used space will provide enough space for the new dirent. + * + * There are two types of blocks in which dirents reside. In a stuffed dinode, + * the dirents begin at offset sizeof(struct gfs2_dinode) from the beginning of + * the block. In leaves, they begin at offset sizeof(struct gfs2_leaf) from the + * beginning of the leaf block. The dirents reside in leaves when + * + * dip->i_di.di_flags & GFS2_DIF_EXHASH is true + * + * Otherwise, the dirents are "linear", within a single stuffed dinode block. + * + * When the dirents are in leaves, the actual contents of the directory file are + * used as an array of 64-bit block pointers pointing to the leaf blocks. The + * dirents are NOT in the directory file itself. There can be more than one + * block pointer in the array that points to the same leaf. In fact, when a + * directory is first converted from linear to exhash, all of the pointers + * point to the same leaf. + * + * When a leaf is completely full, the size of the hash table can be + * doubled unless it is already at the maximum size which is hard coded into + * GFS2_DIR_MAX_DEPTH. After that, leaves are chained together in a linked list, + * but never before the maximum hash table size has been reached. + */ #include <linux/sched.h> #include <linux/slab.h> #include <linux/spinlock.h> -#include <linux/completion.h> #include <linux/buffer_head.h> #include <linux/sort.h> #include <linux/gfs2_ondisk.h> #include <linux/crc32.h> #include <linux/vmalloc.h> -#include <asm/semaphore.h> #include "gfs2.h" #include "lm_interface.h" @@ -92,33 +90,36 @@ typedef int (*leaf_call_t) (struct gfs2_inode *dip, uint32_t index, uint32_t len, uint64_t leaf_no, void *data); -int gfs2_dir_get_buffer(struct gfs2_inode *ip, uint64_t block, int new, - struct buffer_head **bhp) + +int gfs2_dir_get_new_buffer(struct gfs2_inode *ip, uint64_t block, + struct buffer_head **bhp) { struct buffer_head *bh; - int error = 0; - - if (new) { - bh = gfs2_meta_new(ip->i_gl, block); - gfs2_trans_add_bh(ip->i_gl, bh, 1); - gfs2_metatype_set(bh, GFS2_METATYPE_JD, GFS2_FORMAT_JD); - gfs2_buffer_clear_tail(bh, sizeof(struct gfs2_meta_header)); - } else { - error = gfs2_meta_read(ip->i_gl, block, DIO_START | DIO_WAIT, - &bh); - if (error) - return error; - if (gfs2_metatype_check(ip->i_sbd, bh, GFS2_METATYPE_JD)) { - brelse(bh); - return -EIO; - } - } + bh = gfs2_meta_new(ip->i_gl, block); + gfs2_trans_add_bh(ip->i_gl, bh, 1); + gfs2_metatype_set(bh, GFS2_METATYPE_JD, GFS2_FORMAT_JD); + gfs2_buffer_clear_tail(bh, sizeof(struct gfs2_meta_header)); *bhp = bh; return 0; } +static int gfs2_dir_get_existing_buffer(struct gfs2_inode *ip, uint64_t block, + struct buffer_head **bhp) +{ + struct buffer_head *bh; + int error; + error = gfs2_meta_read(ip->i_gl, block, DIO_START | DIO_WAIT, &bh); + if (error) + return error; + if (gfs2_metatype_check(ip->i_sbd, bh, GFS2_METATYPE_JD)) { + brelse(bh); + return -EIO; + } + *bhp = bh; + return 0; +} static int gfs2_dir_write_stuffed(struct gfs2_inode *ip, const char *buf, unsigned int offset, unsigned int size) @@ -205,9 +206,11 @@ static int gfs2_dir_write_data(struct gfs2_inode *ip, const char *buf, goto fail; } - error = gfs2_dir_get_buffer(ip, dblock, - (amount == sdp->sd_jbsize) ? - 1 : new, &bh); + if (amount == sdp->sd_jbsize || new) + error = gfs2_dir_get_new_buffer(ip, dblock, &bh); + else + error = gfs2_dir_get_existing_buffer(ip, dblock, &bh); + if (error) goto fail; @@ -321,7 +324,10 @@ static int gfs2_dir_read_data(struct gfs2_inode *ip, char *buf, gfs2_meta_ra(ip->i_gl, dblock, extlen); if (dblock) { - error = gfs2_dir_get_buffer(ip, dblock, new, &bh); + if (new) + error = gfs2_dir_get_new_buffer(ip, dblock, &bh); + else + error = gfs2_dir_get_existing_buffer(ip, dblock, &bh); if (error) goto fail; dblock++; |