| Message ID | 20220614160603.20566-3-jack@suse.cz |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ext4: Fix possible fs corruption due to xattr races | expand |
On 22/06/14 06:05PM, Jan Kara wrote: > Currently we remove EA inode from mbcache as soon as its xattr refcount > drops to zero. However there can be pending attempts to reuse the inode > and thus refcount handling code has to handle the situation when > refcount increases from zero anyway. So save some work and just keep EA > inode in mbcache until it is getting evicted. At that moment we are sure > following iget() of EA inode will fail anyway (or wait for eviction to > finish and load things from the disk again) and so removing mbcache > entry at that moment is fine and simplifies the code a bit. > > CC: stable@vger.kernel.org > Fixes: 82939d7999df ("ext4: convert to mbcache2") > Signed-off-by: Jan Kara <jack@suse.cz> > --- > fs/ext4/inode.c | 2 ++ > fs/ext4/xattr.c | 24 ++++++++---------------- > fs/ext4/xattr.h | 1 + > 3 files changed, 11 insertions(+), 16 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 3dce7d058985..7450ee734262 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -177,6 +177,8 @@ void ext4_evict_inode(struct inode *inode) > > trace_ext4_evict_inode(inode); > > + if (EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL) > + ext4_evict_ea_inode(inode); > if (inode->i_nlink) { > /* > * When journalling data dirty buffers are tracked only in the > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c > index 042325349098..7fc40fb1e6b3 100644 > --- a/fs/ext4/xattr.c > +++ b/fs/ext4/xattr.c > @@ -436,6 +436,14 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino, > return err; > } > > +/* Remove entry from mbcache when EA inode is getting evicted */ > +void ext4_evict_ea_inode(struct inode *inode) > +{ > + if (EA_INODE_CACHE(inode)) > + mb_cache_entry_delete(EA_INODE_CACHE(inode), > + ext4_xattr_inode_get_hash(inode), inode->i_ino); > +} > + > static int > ext4_xattr_inode_verify_hashes(struct inode *ea_inode, > struct ext4_xattr_entry *entry, void *buffer, > @@ -976,10 +984,8 @@ int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode, > static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, > int ref_change) > { > - struct mb_cache *ea_inode_cache = EA_INODE_CACHE(ea_inode); > struct ext4_iloc iloc; > s64 ref_count; > - u32 hash; > int ret; > > inode_lock(ea_inode); > @@ -1002,14 +1008,6 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, > > set_nlink(ea_inode, 1); > ext4_orphan_del(handle, ea_inode); > - > - if (ea_inode_cache) { > - hash = ext4_xattr_inode_get_hash(ea_inode); > - mb_cache_entry_create(ea_inode_cache, > - GFP_NOFS, hash, > - ea_inode->i_ino, > - true /* reusable */); > - } Ok, so if I understand this correctly, since we are not immediately removing the ea_inode_cache entry when the recount reaches 0, hence when the refcount is reaches 1 from 0, we need not create mb_cache entry is it? Is this since the entry never got deleted in the first place? But what happens when the entry is created the very first time? I might need to study xattr code to understand how this condition is taken care. -ritesh > } > } else { > WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld", > @@ -1022,12 +1020,6 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, > > clear_nlink(ea_inode); > ext4_orphan_add(handle, ea_inode); > - > - if (ea_inode_cache) { > - hash = ext4_xattr_inode_get_hash(ea_inode); > - mb_cache_entry_delete(ea_inode_cache, hash, > - ea_inode->i_ino); > - } > } > } > > diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h > index 77efb9a627ad..060b7a2f485c 100644 > --- a/fs/ext4/xattr.h > +++ b/fs/ext4/xattr.h > @@ -178,6 +178,7 @@ extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array); > > extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize, > struct ext4_inode *raw_inode, handle_t *handle); > +extern void ext4_evict_ea_inode(struct inode *inode); > > extern const struct xattr_handler *ext4_xattr_handlers[]; > > -- > 2.35.3 >
On Thu 16-06-22 20:31:18, Ritesh Harjani wrote: > On 22/06/14 06:05PM, Jan Kara wrote: > > Currently we remove EA inode from mbcache as soon as its xattr refcount > > drops to zero. However there can be pending attempts to reuse the inode > > and thus refcount handling code has to handle the situation when > > refcount increases from zero anyway. So save some work and just keep EA > > inode in mbcache until it is getting evicted. At that moment we are sure > > following iget() of EA inode will fail anyway (or wait for eviction to > > finish and load things from the disk again) and so removing mbcache > > entry at that moment is fine and simplifies the code a bit. > > > > CC: stable@vger.kernel.org > > Fixes: 82939d7999df ("ext4: convert to mbcache2") > > Signed-off-by: Jan Kara <jack@suse.cz> > > --- > > fs/ext4/inode.c | 2 ++ > > fs/ext4/xattr.c | 24 ++++++++---------------- > > fs/ext4/xattr.h | 1 + > > 3 files changed, 11 insertions(+), 16 deletions(-) > > > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > > index 3dce7d058985..7450ee734262 100644 > > --- a/fs/ext4/inode.c > > +++ b/fs/ext4/inode.c > > @@ -177,6 +177,8 @@ void ext4_evict_inode(struct inode *inode) > > > > trace_ext4_evict_inode(inode); > > > > + if (EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL) > > + ext4_evict_ea_inode(inode); > > if (inode->i_nlink) { > > /* > > * When journalling data dirty buffers are tracked only in the > > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c > > index 042325349098..7fc40fb1e6b3 100644 > > --- a/fs/ext4/xattr.c > > +++ b/fs/ext4/xattr.c > > @@ -436,6 +436,14 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino, > > return err; > > } > > > > +/* Remove entry from mbcache when EA inode is getting evicted */ > > +void ext4_evict_ea_inode(struct inode *inode) > > +{ > > + if (EA_INODE_CACHE(inode)) > > + mb_cache_entry_delete(EA_INODE_CACHE(inode), > > + ext4_xattr_inode_get_hash(inode), inode->i_ino); > > +} > > + > > static int > > ext4_xattr_inode_verify_hashes(struct inode *ea_inode, > > struct ext4_xattr_entry *entry, void *buffer, > > @@ -976,10 +984,8 @@ int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode, > > static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, > > int ref_change) > > { > > - struct mb_cache *ea_inode_cache = EA_INODE_CACHE(ea_inode); > > struct ext4_iloc iloc; > > s64 ref_count; > > - u32 hash; > > int ret; > > > > inode_lock(ea_inode); > > @@ -1002,14 +1008,6 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, > > > > set_nlink(ea_inode, 1); > > ext4_orphan_del(handle, ea_inode); > > - > > - if (ea_inode_cache) { > > - hash = ext4_xattr_inode_get_hash(ea_inode); > > - mb_cache_entry_create(ea_inode_cache, > > - GFP_NOFS, hash, > > - ea_inode->i_ino, > > - true /* reusable */); > > - } > > Ok, so if I understand this correctly, since we are not immediately removing the > ea_inode_cache entry when the recount reaches 0, hence when the refcount is > reaches 1 from 0, we need not create mb_cache entry is it? > Is this since the entry never got deleted in the first place? Correct. > But what happens when the entry is created the very first time? > I might need to study xattr code to understand how this condition is > taken care. There are other places that take care of creating the entry in that case. E.g. ext4_xattr_inode_get() or ext4_xattr_inode_lookup_create(). Honza
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 3dce7d058985..7450ee734262 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -177,6 +177,8 @@ void ext4_evict_inode(struct inode *inode) trace_ext4_evict_inode(inode); + if (EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL) + ext4_evict_ea_inode(inode); if (inode->i_nlink) { /* * When journalling data dirty buffers are tracked only in the diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 042325349098..7fc40fb1e6b3 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -436,6 +436,14 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino, return err; } +/* Remove entry from mbcache when EA inode is getting evicted */ +void ext4_evict_ea_inode(struct inode *inode) +{ + if (EA_INODE_CACHE(inode)) + mb_cache_entry_delete(EA_INODE_CACHE(inode), + ext4_xattr_inode_get_hash(inode), inode->i_ino); +} + static int ext4_xattr_inode_verify_hashes(struct inode *ea_inode, struct ext4_xattr_entry *entry, void *buffer, @@ -976,10 +984,8 @@ int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode, static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, int ref_change) { - struct mb_cache *ea_inode_cache = EA_INODE_CACHE(ea_inode); struct ext4_iloc iloc; s64 ref_count; - u32 hash; int ret; inode_lock(ea_inode); @@ -1002,14 +1008,6 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, set_nlink(ea_inode, 1); ext4_orphan_del(handle, ea_inode); - - if (ea_inode_cache) { - hash = ext4_xattr_inode_get_hash(ea_inode); - mb_cache_entry_create(ea_inode_cache, - GFP_NOFS, hash, - ea_inode->i_ino, - true /* reusable */); - } } } else { WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld", @@ -1022,12 +1020,6 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode, clear_nlink(ea_inode); ext4_orphan_add(handle, ea_inode); - - if (ea_inode_cache) { - hash = ext4_xattr_inode_get_hash(ea_inode); - mb_cache_entry_delete(ea_inode_cache, hash, - ea_inode->i_ino); - } } } diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h index 77efb9a627ad..060b7a2f485c 100644 --- a/fs/ext4/xattr.h +++ b/fs/ext4/xattr.h @@ -178,6 +178,7 @@ extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array); extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize, struct ext4_inode *raw_inode, handle_t *handle); +extern void ext4_evict_ea_inode(struct inode *inode); extern const struct xattr_handler *ext4_xattr_handlers[];
Currently we remove EA inode from mbcache as soon as its xattr refcount drops to zero. However there can be pending attempts to reuse the inode and thus refcount handling code has to handle the situation when refcount increases from zero anyway. So save some work and just keep EA inode in mbcache until it is getting evicted. At that moment we are sure following iget() of EA inode will fail anyway (or wait for eviction to finish and load things from the disk again) and so removing mbcache entry at that moment is fine and simplifies the code a bit. CC: stable@vger.kernel.org Fixes: 82939d7999df ("ext4: convert to mbcache2") Signed-off-by: Jan Kara <jack@suse.cz> --- fs/ext4/inode.c | 2 ++ fs/ext4/xattr.c | 24 ++++++++---------------- fs/ext4/xattr.h | 1 + 3 files changed, 11 insertions(+), 16 deletions(-)