diff options
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 148 |
1 files changed, 133 insertions, 15 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 2b96ca68dc10..793d4d571d8d 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4377,6 +4377,123 @@ static struct extent_map *get_extent_skip_holes(struct inode *inode, return NULL; } +/* + * To cache previous fiemap extent + * + * Will be used for merging fiemap extent + */ +struct fiemap_cache { + u64 offset; + u64 phys; + u64 len; + u32 flags; + bool cached; +}; + +/* + * Helper to submit fiemap extent. + * + * Will try to merge current fiemap extent specified by @offset, @phys, + * @len and @flags with cached one. + * And only when we fails to merge, cached one will be submitted as + * fiemap extent. + * + * Return value is the same as fiemap_fill_next_extent(). + */ +static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo, + struct fiemap_cache *cache, + u64 offset, u64 phys, u64 len, u32 flags) +{ + int ret = 0; + + if (!cache->cached) + goto assign; + + /* + * Sanity check, extent_fiemap() should have ensured that new + * fiemap extent won't overlap with cahced one. + * Not recoverable. + * + * NOTE: Physical address can overlap, due to compression + */ + if (cache->offset + cache->len > offset) { + WARN_ON(1); + return -EINVAL; + } + + /* + * Only merges fiemap extents if + * 1) Their logical addresses are continuous + * + * 2) Their physical addresses are continuous + * So truly compressed (physical size smaller than logical size) + * extents won't get merged with each other + * + * 3) Share same flags except FIEMAP_EXTENT_LAST + * So regular extent won't get merged with prealloc extent + */ + if (cache->offset + cache->len == offset && + cache->phys + cache->len == phys && + (cache->flags & ~FIEMAP_EXTENT_LAST) == + (flags & ~FIEMAP_EXTENT_LAST)) { + cache->len += len; + cache->flags |= flags; + goto try_submit_last; + } + + /* Not mergeable, need to submit cached one */ + ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys, + cache->len, cache->flags); + cache->cached = false; + if (ret) + return ret; +assign: + cache->cached = true; + cache->offset = offset; + cache->phys = phys; + cache->len = len; + cache->flags = flags; +try_submit_last: + if (cache->flags & FIEMAP_EXTENT_LAST) { + ret = fiemap_fill_next_extent(fieinfo, cache->offset, + cache->phys, cache->len, cache->flags); + cache->cached = false; + } + return ret; +} + +/* + * Sanity check for fiemap cache + * + * All fiemap cache should be submitted by emit_fiemap_extent() + * Iteration should be terminated either by last fiemap extent or + * fieinfo->fi_extents_max. + * So no cached fiemap should exist. + */ +static int check_fiemap_cache(struct btrfs_fs_info *fs_info, + struct fiemap_extent_info *fieinfo, + struct fiemap_cache *cache) +{ + int ret; + + if (!cache->cached) + return 0; + + /* Small and recoverbale problem, only to info developer */ +#ifdef CONFIG_BTRFS_DEBUG + WARN_ON(1); +#endif + btrfs_warn(fs_info, + "unhandled fiemap cache detected: offset=%llu phys=%llu len=%llu flags=0x%x", + cache->offset, cache->phys, cache->len, cache->flags); + ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys, + cache->len, cache->flags); + cache->cached = false; + if (ret > 0) + ret = 0; + return ret; +} + int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, __u64 start, __u64 len, get_extent_t *get_extent) { @@ -4394,6 +4511,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, struct extent_state *cached_state = NULL; struct btrfs_path *path; struct btrfs_root *root = BTRFS_I(inode)->root; + struct fiemap_cache cache = { 0 }; int end = 0; u64 em_start = 0; u64 em_len = 0; @@ -4573,8 +4691,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, flags |= FIEMAP_EXTENT_LAST; end = 1; } - ret = fiemap_fill_next_extent(fieinfo, em_start, disko, - em_len, flags); + ret = emit_fiemap_extent(fieinfo, &cache, em_start, disko, + em_len, flags); if (ret) { if (ret == 1) ret = 0; @@ -4582,6 +4700,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, } } out_free: + if (!ret) + ret = check_fiemap_cache(root->fs_info, fieinfo, &cache); free_extent_map(em); out: btrfs_free_path(path); @@ -5322,9 +5442,8 @@ unlock_exit: return ret; } -void read_extent_buffer(struct extent_buffer *eb, void *dstv, - unsigned long start, - unsigned long len) +void read_extent_buffer(const struct extent_buffer *eb, void *dstv, + unsigned long start, unsigned long len) { size_t cur; size_t offset; @@ -5353,9 +5472,9 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv, } } -int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv, - unsigned long start, - unsigned long len) +int read_extent_buffer_to_user(const struct extent_buffer *eb, + void __user *dstv, + unsigned long start, unsigned long len) { size_t cur; size_t offset; @@ -5395,10 +5514,10 @@ int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv, * return 1 if the item spans two pages. * return -EINVAL otherwise. */ -int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start, - unsigned long min_len, char **map, - unsigned long *map_start, - unsigned long *map_len) +int map_private_extent_buffer(const struct extent_buffer *eb, + unsigned long start, unsigned long min_len, + char **map, unsigned long *map_start, + unsigned long *map_len) { size_t offset = start & (PAGE_SIZE - 1); char *kaddr; @@ -5432,9 +5551,8 @@ int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start, return 0; } -int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv, - unsigned long start, - unsigned long len) +int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv, + unsigned long start, unsigned long len) { size_t cur; size_t offset; |