From 4fbf4291aa15926cd4fdca0ffe9122e89d0459db Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:11:04 +0000 Subject: FS-Cache: Allow the current state of all objects to be dumped Allow the current state of all fscache objects to be dumped by doing: cat /proc/fs/fscache/objects By default, all objects and all fields will be shown. This can be restricted by adding a suitable key to one of the caller's keyrings (such as the session keyring): keyctl add user fscache:objlist "" @s The are: K Show hexdump of object key (don't show if not given) A Show hexdump of object aux data (don't show if not given) And paired restrictions: C Show objects that have a cookie c Show objects that don't have a cookie B Show objects that are busy b Show objects that aren't busy W Show objects that have pending writes w Show objects that don't have pending writes R Show objects that have outstanding reads r Show objects that don't have outstanding reads S Show objects that have slow work queued s Show objects that don't have slow work queued If neither side of a restriction pair is given, then both are implied. For example: keyctl add user fscache:objlist KB @s shows objects that are busy, and lists their object keys, but does not dump their auxiliary data. It also implies "CcWwRrSs", but as 'B' is given, 'b' is not implied. Signed-off-by: David Howells --- fs/cachefiles/interface.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/cachefiles/interface.c') diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index 431accd475a7..dd7f852746cb 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -331,6 +331,7 @@ static void cachefiles_put_object(struct fscache_object *_object) } cache = object->fscache.cache; + fscache_object_destroy(&object->fscache); kmem_cache_free(cachefiles_object_jar, object); fscache_object_destroyed(cache); } -- cgit v1.2.2 From a17754fb8c28af19cd70dcbec6d5b0773b94e0c1 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:11:52 +0000 Subject: CacheFiles: Don't write a full page if there's only a partial page to cache cachefiles_write_page() writes a full page to the backing file for the last page of the netfs file, even if the netfs file's last page is only a partial page. This causes the EOF on the backing file to be extended beyond the EOF of the netfs, and thus the backing file will be truncated by cachefiles_attr_changed() called from cachefiles_lookup_object(). So we need to limit the write we make to the backing file on that last page such that it doesn't push the EOF too far. Also, if a backing file that has a partial page at the end is expanded, we discard the partial page and refetch it on the basis that we then have a hole in the file with invalid data, and should the power go out... A better way to deal with this could be to record a note that the partial page contains invalid data until the correct data is written into it. This isn't a problem for netfs's that discard the whole backing file if the file size changes (such as NFS). Signed-off-by: David Howells --- fs/cachefiles/interface.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) (limited to 'fs/cachefiles/interface.c') diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index dd7f852746cb..8e67abf05985 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -404,12 +404,26 @@ static int cachefiles_attr_changed(struct fscache_object *_object) if (oi_size == ni_size) return 0; - newattrs.ia_size = ni_size; - newattrs.ia_valid = ATTR_SIZE; - cachefiles_begin_secure(cache, &saved_cred); mutex_lock(&object->backer->d_inode->i_mutex); + + /* if there's an extension to a partial page at the end of the backing + * file, we need to discard the partial page so that we pick up new + * data after it */ + if (oi_size & ~PAGE_MASK && ni_size > oi_size) { + _debug("discard tail %llx", oi_size); + newattrs.ia_valid = ATTR_SIZE; + newattrs.ia_size = oi_size & PAGE_MASK; + ret = notify_change(object->backer, &newattrs); + if (ret < 0) + goto truncate_failed; + } + + newattrs.ia_valid = ATTR_SIZE; + newattrs.ia_size = ni_size; ret = notify_change(object->backer, &newattrs); + +truncate_failed: mutex_unlock(&object->backer->d_inode->i_mutex); cachefiles_end_secure(cache, saved_cred); -- cgit v1.2.2 From fee096deb4f33897937b974cb2c5168bab7935be Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:12:05 +0000 Subject: CacheFiles: Catch an overly long wait for an old active object Catch an overly long wait for an old, dying active object when we want to replace it with a new one. The probability is that all the slow-work threads are hogged, and the delete can't get a look in. What we do instead is: (1) if there's nothing in the slow work queue, we sleep until either the dying object has finished dying or there is something in the slow work queue behind which we can queue our object. (2) if there is something in the slow work queue, we return ETIMEDOUT to fscache_lookup_object(), which then puts us back on the slow work queue, presumably behind the deletion that we're blocked by. We are then deferred for a while until we work our way back through the queue - without blocking a slow-work thread unnecessarily. A backtrace similar to the following may appear in the log without this patch: INFO: task kslowd004:5711 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kslowd004 D 0000000000000000 0 5711 2 0x00000080 ffff88000340bb80 0000000000000046 ffff88002550d000 0000000000000000 ffff88002550d000 0000000000000007 ffff88000340bfd8 ffff88002550d2a8 000000000000ddf0 00000000000118c0 00000000000118c0 ffff88002550d2a8 Call Trace: [] ? trace_hardirqs_on+0xd/0xf [] ? cachefiles_wait_bit+0x0/0xd [cachefiles] [] cachefiles_wait_bit+0x9/0xd [cachefiles] [] __wait_on_bit+0x43/0x76 [] ? ext3_xattr_get+0x1ec/0x270 [] out_of_line_wait_on_bit+0x69/0x74 [] ? cachefiles_wait_bit+0x0/0xd [cachefiles] [] ? wake_bit_function+0x0/0x2e [] cachefiles_mark_object_active+0x203/0x23b [cachefiles] [] cachefiles_walk_to_object+0x558/0x827 [cachefiles] [] cachefiles_lookup_object+0xac/0x12a [cachefiles] [] fscache_lookup_object+0x1c7/0x214 [fscache] [] fscache_object_state_machine+0xa5/0x52d [fscache] [] fscache_object_slow_work_execute+0x5f/0xa0 [fscache] [] slow_work_execute+0x18f/0x2d1 [] slow_work_thread+0x1c5/0x308 [] ? autoremove_wake_function+0x0/0x34 [] ? slow_work_thread+0x0/0x308 [] kthread+0x7a/0x82 [] child_rip+0xa/0x20 [] ? restore_args+0x0/0x30 [] ? kthread+0x0/0x82 [] ? child_rip+0x0/0x20 1 lock held by kslowd004/5711: #0: (&sb->s_type->i_mutex_key#7/1){+.+.+.}, at: [] cachefiles_walk_to_object+0x1b3/0x827 [cachefiles] Signed-off-by: David Howells --- fs/cachefiles/interface.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'fs/cachefiles/interface.c') diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index 8e67abf05985..9d3c426044ae 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -114,8 +114,9 @@ nomem_lookup_data: /* * attempt to look up the nominated node in this cache + * - return -ETIMEDOUT to be scheduled again */ -static void cachefiles_lookup_object(struct fscache_object *_object) +static int cachefiles_lookup_object(struct fscache_object *_object) { struct cachefiles_lookup_data *lookup_data; struct cachefiles_object *parent, *object; @@ -145,13 +146,14 @@ static void cachefiles_lookup_object(struct fscache_object *_object) object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) cachefiles_attr_changed(&object->fscache); - if (ret < 0) { + if (ret < 0 && ret != -ETIMEDOUT) { printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n", ret); fscache_object_lookup_error(&object->fscache); } _leave(" [%d]", ret); + return ret; } /* -- cgit v1.2.2 From 14e69647c868459bcb910f771851ca7c699efd21 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 19 Nov 2009 18:12:08 +0000 Subject: CacheFiles: Don't log lookup/create failing with ENOBUFS Don't log the CacheFiles lookup/create object routined failing with ENOBUFS as under high memory load or high cache load they can do this quite a lot. This error simply means that the requested object cannot be created on disk due to lack of space, or due to failure of the backing filesystem to find sufficient resources. Signed-off-by: David Howells --- fs/cachefiles/interface.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'fs/cachefiles/interface.c') diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index 9d3c426044ae..27089311fbea 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -147,8 +147,9 @@ static int cachefiles_lookup_object(struct fscache_object *_object) cachefiles_attr_changed(&object->fscache); if (ret < 0 && ret != -ETIMEDOUT) { - printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n", - ret); + if (ret != -ENOBUFS) + printk(KERN_WARNING + "CacheFiles: Lookup failed error %d\n", ret); fscache_object_lookup_error(&object->fscache); } -- cgit v1.2.2