diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 49e42635e3ac..8b24805e62ee 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -114,6 +114,9 @@ struct fuse_inode { /* position at end of cache (position of next entry) */ loff_t pos; + /* version of the cache */ + u64 version; + /* protects above fields */ spinlock_t lock; } rdc; @@ -176,6 +179,10 @@ struct fuse_file { /* Offset in cache */ loff_t cache_off; + + /* Version of cache we are reading */ + u64 version; + } readdir; /** RB node to be linked on fuse_conn->polled_files */ diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 892efe6351eb..eef2ae713f75 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -104,6 +104,7 @@ static struct inode *fuse_alloc_inode(struct super_block *sb) fi->rdc.cached = false; fi->rdc.size = 0; fi->rdc.pos = 0; + fi->rdc.version = 0; mutex_init(&fi->mutex); fi->forget = fuse_alloc_forget(); if (!fi->forget) { diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c index 5bdc0b945d72..18318cc31c05 100644 --- a/fs/fuse/readdir.c +++ b/fs/fuse/readdir.c @@ -36,6 +36,7 @@ static void fuse_add_dirent_to_cache(struct file *file, pgoff_t index; struct page *page; loff_t size; + u64 version; unsigned int offset; void *addr; @@ -48,6 +49,7 @@ static void fuse_add_dirent_to_cache(struct file *file, spin_unlock(&fi->rdc.lock); return; } + version = fi->rdc.version; size = fi->rdc.size; offset = size & ~PAGE_MASK; index = size >> PAGE_SHIFT; @@ -69,7 +71,8 @@ static void fuse_add_dirent_to_cache(struct file *file, spin_lock(&fi->rdc.lock); /* Raced with another readdir */ - if (fi->rdc.size != size || WARN_ON(fi->rdc.pos != pos)) + if (fi->rdc.version != version || fi->rdc.size != size || + WARN_ON(fi->rdc.pos != pos)) goto unlock; addr = kmap_atomic(page); @@ -396,6 +399,14 @@ static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff, return res; } +static void fuse_rdc_reset(struct fuse_inode *fi) +{ + fi->rdc.cached = false; + fi->rdc.version++; + fi->rdc.size = 0; + fi->rdc.pos = 0; +} + #define UNCACHED 1 static int fuse_readdir_cached(struct file *file, struct dir_context *ctx) @@ -421,6 +432,21 @@ static int fuse_readdir_cached(struct file *file, struct dir_context *ctx) spin_unlock(&fi->rdc.lock); return UNCACHED; } + /* + * If cache version changed since the last getdents() call, then reset + * the cache stream. + */ + if (ff->readdir.version != fi->rdc.version) { + ff->readdir.pos = 0; + ff->readdir.cache_off = 0; + } + /* + * If at the beginning of the cache, than reset version to + * current. + */ + if (ff->readdir.pos == 0) + ff->readdir.version = fi->rdc.version; + WARN_ON(fi->rdc.size < ff->readdir.cache_off); index = ff->readdir.cache_off >> PAGE_SHIFT; @@ -437,13 +463,30 @@ static int fuse_readdir_cached(struct file *file, struct dir_context *ctx) page = find_get_page_flags(file->f_mapping, index, FGP_ACCESSED | FGP_LOCK); + spin_lock(&fi->rdc.lock); if (!page) { /* * Uh-oh: page gone missing, cache is useless */ + if (fi->rdc.version == ff->readdir.version) + fuse_rdc_reset(fi); + spin_unlock(&fi->rdc.lock); return UNCACHED; } + /* Make sure it's still the same version after getting the page. */ + if (ff->readdir.version != fi->rdc.version) { + spin_unlock(&fi->rdc.lock); + unlock_page(page); + put_page(page); + goto retry; + } + spin_unlock(&fi->rdc.lock); + + /* + * Contents of the page are now protected against changing by holding + * the page lock. + */ addr = kmap(page); res = fuse_parse_cache(ff, addr, size, ctx); kunmap(page);