diff options
Diffstat (limited to 'fs/fat/file.c')
-rw-r--r-- | fs/fat/file.c | 78 |
1 files changed, 77 insertions, 1 deletions
diff --git a/fs/fat/file.c b/fs/fat/file.c index 85f79a89e747..92e9e753b554 100644 --- a/fs/fat/file.c +++ b/fs/fat/file.c @@ -17,8 +17,12 @@ #include <linux/blkdev.h> #include <linux/fsnotify.h> #include <linux/security.h> +#include <linux/falloc.h> #include "fat.h" +static long fat_fallocate(struct file *file, int mode, + loff_t offset, loff_t len); + static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr) { u32 attr; @@ -182,6 +186,7 @@ const struct file_operations fat_file_operations = { #endif .fsync = fat_file_fsync, .splice_read = generic_file_splice_read, + .fallocate = fat_fallocate, }; static int fat_cont_expand(struct inode *inode, loff_t size) @@ -220,6 +225,75 @@ out: return err; } +/* + * Preallocate space for a file. This implements fat's fallocate file + * operation, which gets called from sys_fallocate system call. User + * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set + * we just allocate clusters without zeroing them out. Otherwise we + * allocate and zero out clusters via an expanding truncate. + */ +static long fat_fallocate(struct file *file, int mode, + loff_t offset, loff_t len) +{ + int cluster; + int nr_cluster; /* Number of clusters to be allocated */ + loff_t mm_bytes; /* Number of bytes to be allocated for file */ + struct inode *inode = file->f_mapping->host; + struct super_block *sb = inode->i_sb; + struct msdos_sb_info *sbi = MSDOS_SB(sb); + int err = 0; + + /* No support for hole punch or other fallocate flags. */ + if (mode & ~FALLOC_FL_KEEP_SIZE) + return -EOPNOTSUPP; + + /* No support for dir */ + if (!S_ISREG(inode->i_mode)) + return -EOPNOTSUPP; + + mutex_lock(&inode->i_mutex); + if ((offset + len) <= MSDOS_I(inode)->i_disksize) + goto error; + + err = inode_newsize_ok(inode, (len + offset)); + if (err) + goto error; + + if (mode & FALLOC_FL_KEEP_SIZE) { + /* First compute the number of clusters to be allocated */ + mm_bytes = offset + len - round_up(MSDOS_I(inode)->i_disksize, + sbi->cluster_size); + nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >> + sbi->cluster_bits; + + /* Start the allocation.We are not zeroing out the clusters */ + while (nr_cluster-- > 0) { + err = fat_alloc_clusters(inode, &cluster, 1); + if (err) { + fat_msg(sb, KERN_ERR, + "fat_fallocate(): fat_alloc_clusters() error"); + goto error; + } + err = fat_chain_add(inode, cluster, 1); + if (err) { + fat_free_clusters(inode, cluster); + goto error; + } + MSDOS_I(inode)->i_disksize += sbi->cluster_size; + } + } else { + /* This is just an expanding truncate */ + err = fat_cont_expand(inode, (offset + len)); + if (err) + fat_msg(sb, KERN_ERR, + "fat_fallocate(): fat_cont_expand() error"); + } + +error: + mutex_unlock(&inode->i_mutex); + return err; +} + /* Free all clusters after the skip'th cluster. */ static int fat_free(struct inode *inode, int skip) { @@ -300,8 +374,10 @@ void fat_truncate_blocks(struct inode *inode, loff_t offset) * This protects against truncating a file bigger than it was then * trying to write into the hole. */ - if (MSDOS_I(inode)->mmu_private > offset) + if (MSDOS_I(inode)->i_disksize > offset) { MSDOS_I(inode)->mmu_private = offset; + MSDOS_I(inode)->i_disksize = offset; + } nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits; |