diff options
Diffstat (limited to 'fs/ext4/inode.c')
| -rw-r--r-- | fs/ext4/inode.c | 62 |
1 files changed, 54 insertions, 8 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 7dd9b50..8fab233 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -382,7 +382,7 @@ no_block: * @inode: owner * @ind: descriptor of indirect block. * - * This function returns the prefered place for block allocation. + * This function returns the preferred place for block allocation. * It is used when heuristic for sequential allocation fails. * Rules are: * + if there is a block to the left of our position - allocate near it. @@ -403,6 +403,7 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind) __le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data; __le32 *p; ext4_fsblk_t bg_start; + ext4_fsblk_t last_block; ext4_grpblk_t colour; /* Try to find previous block */ @@ -420,18 +421,23 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind) * into the same cylinder group then. */ bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group); - colour = (current->pid % 16) * + last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; + + if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) + colour = (current->pid % 16) * (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); + else + colour = (current->pid % 16) * ((last_block - bg_start) / 16); return bg_start + colour; } /** - * ext4_find_goal - find a prefered place for allocation. + * ext4_find_goal - find a preferred place for allocation. * @inode: owner * @block: block we want * @partial: pointer to the last triple within a chain * - * Normally this function find the prefered place for block allocation, + * Normally this function find the preferred place for block allocation, * returns it. */ static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block, @@ -768,7 +774,6 @@ err_out: * * `handle' can be NULL if create == 0. * - * The BKL may not be held on entry here. Be sure to take it early. * return > 0, # of blocks mapped or allocated. * return = 0, if plain lookup failed. * return < 0, error case. @@ -903,11 +908,38 @@ out: */ #define DIO_CREDITS 25 + +/* + * + * + * ext4_ext4 get_block() wrapper function + * It will do a look up first, and returns if the blocks already mapped. + * Otherwise it takes the write lock of the i_data_sem and allocate blocks + * and store the allocated blocks in the result buffer head and mark it + * mapped. + * + * If file type is extents based, it will call ext4_ext_get_blocks(), + * Otherwise, call with ext4_get_blocks_handle() to handle indirect mapping + * based files + * + * On success, it returns the number of blocks being mapped or allocate. + * if create==0 and the blocks are pre-allocated and uninitialized block, + * the result buffer head is unmapped. If the create ==1, it will make sure + * the buffer head is mapped. + * + * It returns 0 if plain look up failed (blocks have not been allocated), in + * that casem, buffer head is unmapped + * + * It returns the error in case of allocation failure. + */ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block, unsigned long max_blocks, struct buffer_head *bh, int create, int extend_disksize) { int retval; + + clear_buffer_mapped(bh); + /* * Try to see if we can get the block without requesting * for new file system block. @@ -921,12 +953,26 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block, inode, block, max_blocks, bh, 0, 0); } up_read((&EXT4_I(inode)->i_data_sem)); - if (!create || (retval > 0)) + + /* If it is only a block(s) look up */ + if (!create) + return retval; + + /* + * Returns if the blocks have already allocated + * + * Note that if blocks have been preallocated + * ext4_ext_get_block() returns th create = 0 + * with buffer head unmapped. + */ + if (retval > 0 && buffer_mapped(bh)) return retval; /* - * We need to allocate new blocks which will result - * in i_data update + * New blocks allocate and/or writing to uninitialized extent + * will possibly result in updating i_data, so we take + * the write lock of i_data_sem, and call get_blocks() + * with create == 1 flag. */ down_write((&EXT4_I(inode)->i_data_sem)); /* |
